Remove EMailExtension.

EMailExtension is now too trivial to keep as a standalone interface.
Add a 'mime_types' string array to the EMailFormatterExtension and
EMailFormatterParser interface structs.

Alter e_mail_extension_registry_add_extension() to take a 'mime_types'
string array and the GType of an extension to instantiate, rather than
the extension instance directly.

e_mail_extension_registry_remove_extension() is no longer needed.

51 files changed, 124 insertions, 617 deletions

diff --git a/em-format/Makefile.am b/em-format/Makefile.am
index cafe098dc0..6e45b0f6f1 100644
--- a/em-format/Makefile.am
+++ b/em-format/Makefile.am
@@ -4,7 +4,6 @@ privsolib_LTLIBRARIES = libemformat.la
 
 emformatinclude_HEADERS =				\
 	e-mail-extension-registry.h			\
-	e-mail-extension.h				\
 	e-mail-formatter-extension.h			\
 	e-mail-formatter.h				\
 	e-mail-formatter-print.h			\
@@ -40,7 +39,6 @@ endif
 libemformat_la_SOURCES =				\
 	$(emformatinclude_HEADERS)			\
 	e-mail-extension-registry.c			\
-	e-mail-extension.c				\
 	e-mail-inline-filter.c				\
 	e-mail-format-extensions.c			\
 	e-mail-format-extensions.h			\
diff --git a/em-format/e-mail-extension-registry.c b/em-format/e-mail-extension-registry.c
index 41a3d6f664..cc6da4b9a8 100644
--- a/em-format/e-mail-extension-registry.c
+++ b/em-format/e-mail-extension-registry.c
@@ -19,7 +19,6 @@
 #include <glib-object.h>
 
 #include "e-mail-extension-registry.h"
-#include "e-mail-extension.h"
 #include "e-mail-format-extensions.h"
 #include <libebackend/libebackend.h>
 #include <camel/camel.h>
@@ -96,95 +95,47 @@ e_mail_extension_registry_init (EMailExtensionRegistry *reg)
 
 /**
  * e_mail_extension_registry_add_extension:
- * @reg: An #EMailExtensionRegistry
- * @extension: An #EMailExtension
+ * @reg: an #EMailExtensionRegistry
+ * @mime_types: a %NULL-terminated array of MIME types
+ * @extension_type: the #GType of the extension being added
  *
- * Registrys the @extension as a handler for all mime-types that it is able
- * to handle.
+ * Creates an instance of @extension_type and registers the instance for
+ * all provided MIME types.
  */
 void
 e_mail_extension_registry_add_extension (EMailExtensionRegistry *reg,
-                                         EMailExtension *extension)
+                                         const gchar **mime_types,
+                                         GType extension_type)
 {
-	EMailExtensionInterface *interface;
+	GObject *extension;
 	gint ii;
 
 	g_return_if_fail (E_IS_MAIL_EXTENSION_REGISTRY (reg));
-	g_return_if_fail (E_IS_MAIL_EXTENSION (extension));
-
-	/* One reference per extension is enough */
-	g_object_ref (extension);
+	g_return_if_fail (mime_types != NULL);
+	g_return_if_fail (extension_type != G_TYPE_INVALID);
 
-	interface = E_MAIL_EXTENSION_GET_INTERFACE (extension);
-	if (interface->mime_types == NULL) {
-		g_critical (
-			"%s does not define any MIME types",
-			G_OBJECT_TYPE_NAME (extension));
-		return;
-	}
+	extension = g_object_new (extension_type, NULL);
 
-	for (ii = 0; interface->mime_types[ii] != NULL; ii++) {
+	for (ii = 0; mime_types[ii] != NULL; ii++) {
 		GQueue *queue;
 
 		queue = g_hash_table_lookup (
-			reg->priv->table, interface->mime_types[ii]);
+			reg->priv->table, mime_types[ii]);
 		if (queue == NULL) {
 			queue = g_queue_new ();
-			g_queue_push_head (queue, extension);
 			g_hash_table_insert (
 				reg->priv->table,
-				(gpointer) interface->mime_types[ii],
+				(gpointer) mime_types[ii],
 				queue);
-		} else {
-			g_queue_push_head (queue, extension);
 		}
 
-		if (camel_debug ("emformat:registry")) {
-			printf (
-				"Added extension '%s' for type '%s'\n",
-				G_OBJECT_TYPE_NAME (extension),
-				interface->mime_types[ii]);
-		}
-	}
-}
-
-/**
- * e_mail_extension_registry_remove_extension:
- * @reg: An #EMailExtensionRegistry
- * @extension: An #EMailExtension
- *
- * Removes @extension from the registry.
- */
-void
-e_mail_extension_registry_remove_extension (EMailExtensionRegistry *reg,
-                                            EMailExtension *extension)
-{
-	EMailExtensionInterface *interface;
-	gint ii;
-
-	g_return_if_fail (E_IS_MAIL_EXTENSION_REGISTRY (reg));
-	g_return_if_fail (E_IS_MAIL_EXTENSION (extension));
-
-	interface = E_MAIL_EXTENSION_GET_INTERFACE (extension);
-	if (interface->mime_types == NULL)
-		return;
-
-	for (ii = 0; interface->mime_types[ii] != NULL; ii++) {
-		GQueue *queue;
-
-		queue = g_hash_table_lookup (
-			reg->priv->table,
-			interface->mime_types[ii]);
-		if (queue == NULL)
-			continue;
-
-		g_queue_remove (queue, extension);
+		g_queue_push_head (queue, g_object_ref (extension));
 
 		if (camel_debug ("emformat:registry")) {
 			printf (
-				"Removed extension '%s' from type '%s'\n",
-				G_OBJECT_TYPE_NAME (extension),
-				interface->mime_types[ii]);
+				"Added extension '%s' for type '%s'\n",
+				g_type_name (extension_type),
+				mime_types[ii]);
 		}
 	}
 
diff --git a/em-format/e-mail-extension-registry.h b/em-format/e-mail-extension-registry.h
index a6ddb441e0..4d17b759d7 100644
--- a/em-format/e-mail-extension-registry.h
+++ b/em-format/e-mail-extension-registry.h
@@ -19,7 +19,7 @@
 #ifndef E_MAIL_EXTENSION_REGISTRY_H_
 #define E_MAIL_EXTENSION_REGISTRY_H_
 
-#include <em-format/e-mail-extension.h>
+#include <glib-object.h>
 
 /* Standard GObject macros */
 #define E_TYPE_MAIL_EXTENSION_REGISTRY \
@@ -55,21 +55,18 @@ struct _EMailExtensionRegistry {
 	EMailExtensionRegistryPrivate *priv;
 };
 
-GType		e_mail_extension_registry_get_type	(void);
-
-void		e_mail_extension_registry_add_extension	(EMailExtensionRegistry *reg,
-							 EMailExtension *extension);
-
-void		e_mail_extension_registry_remove_extension
-							(EMailExtensionRegistry *reg,
-							 EMailExtension *extension);
-
+GType		e_mail_extension_registry_get_type
+						(void) G_GNUC_CONST;
+void		e_mail_extension_registry_add_extension
+						(EMailExtensionRegistry *reg,
+						 const gchar **mime_types,
+						 GType extension_type);
 GQueue *	e_mail_extension_registry_get_for_mime_type
-							(EMailExtensionRegistry *reg,
-							 const gchar *mime_type);
-
-GQueue *	e_mail_extension_registry_get_fallback	(EMailExtensionRegistry *reg,
-							 const gchar *mime_type);
+						(EMailExtensionRegistry *reg,
+						 const gchar *mime_type);
+GQueue *	e_mail_extension_registry_get_fallback
+						(EMailExtensionRegistry *reg,
+						 const gchar *mime_type);
 
 G_END_DECLS
 
@@ -109,7 +106,8 @@ struct _EMailParserExtensionRegistry {
 	EMailParserExtensionRegistryPrivate *priv;
 };
 
-GType		e_mail_parser_extension_registry_get_type	(void);
+GType		e_mail_parser_extension_registry_get_type
+						(void) G_GNUC_CONST;
 
 G_END_DECLS
 
@@ -149,7 +147,8 @@ struct _EMailFormatterExtensionRegistry {
 	EMailFormatterExtensionRegistryPrivate *priv;
 };
 
-GType		e_mail_formatter_extension_registry_get_type	(void);
+GType		e_mail_formatter_extension_registry_get_type
+						(void) G_GNUC_CONST;
 
 G_END_DECLS
 
diff --git a/em-format/e-mail-extension.c b/em-format/e-mail-extension.c
deleted file mode 100644
index ee319773c1..0000000000
--- a/em-format/e-mail-extension.c
+++ /dev/null
@@ -1,41 +0,0 @@
-/*
- * e-mail-extension.c
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with the program; if not, see <http://www.gnu.org/licenses/>
- *
- */
-
-#include "e-mail-extension.h"
-
-#include <glib-object.h>
-
-G_DEFINE_INTERFACE (EMailExtension, e_mail_extension, G_TYPE_OBJECT)
-
-static void
-e_mail_extension_default_init (EMailExtensionInterface *iface)
-{
-
-}
-
-/**
- * EMailExtension:
- *
- * The #EMailExtension is an abstract interface for all extensions for
- * #EMailParser and #EmailFormatter.
- *
- * The interface is further extended by #EMailParserExtension and
- * #EMailFormatterExtension interfaces which define final API for both types
- * of extensions.
- */
-
diff --git a/em-format/e-mail-extension.h b/em-format/e-mail-extension.h
deleted file mode 100644
index 4050cce169..0000000000
--- a/em-format/e-mail-extension.h
+++ /dev/null
@@ -1,61 +0,0 @@
-/*
- * e-mail-extension.h
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) version 3.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with the program; if not, see <http://www.gnu.org/licenses/>
- *
- */
-
-#ifndef E_MAIL_EXTENSION_H
-#define E_MAIL_EXTENSION_H
-
-#include <glib-object.h>
-
-/* Standard GObject macros */
-#define E_TYPE_MAIL_EXTENSION \
-	(e_mail_extension_get_type ())
-#define E_MAIL_EXTENSION(obj) \
-	(G_TYPE_CHECK_INSTANCE_CAST \
-	((obj), E_TYPE_MAIL_EXTENSION, EMailExtension))
-#define E_MAIL_EXTENSION_INTERFACE(cls) \
-	(G_TYPE_CHECK_CLASS_CAST \
-	((cls), E_TYPE_MAIL_EXTENSION, EMailExtensionInterface))
-#define E_IS_MAIL_EXTENSION(obj) \
-	(G_TYPE_CHECK_INSTANCE_TYPE \
-	((obj), E_TYPE_MAIL_EXTENSION))
-#define E_IS_MAIL_EXTENSION_INTERFACE(cls) \
-	(G_TYPE_CHECK_CLASS_TYPE \
-	((cls), E_TYPE_MAIL_EXTENSION))
-#define E_MAIL_EXTENSION_GET_INTERFACE(obj) \
-	(G_TYPE_INSTANCE_GET_INTERFACE \
-	((obj), E_TYPE_MAIL_EXTENSION, EMailExtensionInterface))
-
-G_BEGIN_DECLS
-
-typedef struct _EMailExtension EMailExtension;
-typedef struct _EMailExtensionInterface EMailExtensionInterface;
-
-struct _EMailExtensionInterface {
-	GTypeInterface parent_interface;
-
-	/* This is a NULL-terminated array of supported MIME types.
-	 * The MIME types can be exact (e.g. "text/plain") or use a
-	 * wildcard (e.g. "text/ *"). */
-	const gchar **mime_types;
-};
-
-GType		e_mail_extension_get_type		(void) G_GNUC_CONST;
-
-G_END_DECLS
-
-#endif /* E_MAIL_EXTENSION_H */
diff --git a/em-format/e-mail-format-extensions.c b/em-format/e-mail-format-extensions.c
index fa7d5d8683..01162bc9ea 100644
--- a/em-format/e-mail-format-extensions.c
+++ b/em-format/e-mail-format-extensions.c
@@ -86,16 +86,44 @@ static void
 load (EMailExtensionRegistry *ereg,
       TypeFunc *func_array)
 {
-	gint i = 0;
+	gint ii;
 
-	for (i = 0; func_array[i] != NULL; i++) {
-		GType type;
-		EMailExtension *extension;
+	for (ii = 0; func_array[ii] != NULL; ii++) {
+		GType extension_type;
+		GType interface_type;
+		gpointer extension_class;
+		const gchar **mime_types = NULL;
 
-		type = func_array[i]();
-		extension = g_object_new (type, NULL);
+		extension_type = func_array[ii]();
+		extension_class = g_type_class_ref (extension_type);
 
-		e_mail_extension_registry_add_extension (ereg, extension);
+		interface_type = E_TYPE_MAIL_FORMATTER_EXTENSION;
+		if (g_type_is_a (extension_type, interface_type)) {
+			EMailFormatterExtensionInterface *interface;
+
+			interface = g_type_interface_peek (
+				extension_class, interface_type);
+			mime_types = interface->mime_types;
+		}
+
+		interface_type = E_TYPE_MAIL_PARSER_EXTENSION;
+		if (g_type_is_a (extension_type, interface_type)) {
+			EMailParserExtensionInterface *interface;
+
+			interface = g_type_interface_peek (
+				extension_class, interface_type);
+			mime_types = interface->mime_types;
+		}
+
+		if (mime_types != NULL)
+			e_mail_extension_registry_add_extension (
+				ereg, mime_types, extension_type);
+		else
+			g_critical (
+				"%s does not define any MIME types",
+				g_type_name (extension_type));
+
+		g_type_class_unref (extension_class);
 	}
 }
 
diff --git a/em-format/e-mail-formatter-attachment-bar.c b/em-format/e-mail-formatter-attachment-bar.c
index 33b13675a9..160c8af891 100644
--- a/em-format/e-mail-formatter-attachment-bar.c
+++ b/em-format/e-mail-formatter-attachment-bar.c
@@ -37,7 +37,6 @@ typedef struct _EMailFormatterAttachmentBarClass {
 } EMailFormatterAttachmentBarClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterAttachmentBar,
@@ -45,9 +44,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init));
 
@@ -133,6 +129,7 @@ e_mail_formatter_attachment_bar_class_init (EMailFormatterAttachmentBarClass *cl
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_attachment_bar_format;
 	iface->get_widget = emfe_attachment_bar_get_widget;
 	iface->get_display_name = emfe_attachment_bar_get_display_name;
@@ -140,12 +137,6 @@ e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInte
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_attachment_bar_init (EMailFormatterAttachmentBar *extension)
 {
 
diff --git a/em-format/e-mail-formatter-attachment.c b/em-format/e-mail-formatter-attachment.c
index d583801a0a..f637766f1d 100644
--- a/em-format/e-mail-formatter-attachment.c
+++ b/em-format/e-mail-formatter-attachment.c
@@ -49,7 +49,6 @@ typedef struct _EMailFormatterAttachmentClass {
 } EMailFormatterAttachmentClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterAttachment,
@@ -57,9 +56,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init)
 )
@@ -398,6 +394,7 @@ e_mail_formatter_attachment_class_init (EMailFormatterAttachmentClass *class)
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_attachment_format;
 	iface->get_widget = emfe_attachment_get_widget;
 	iface->get_display_name = emfe_attachment_get_display_name;
@@ -405,12 +402,6 @@ e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInte
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_attachment_init (EMailFormatterAttachment *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-error.c b/em-format/e-mail-formatter-error.c
index 0c183a0aeb..8c8615662c 100644
--- a/em-format/e-mail-formatter-error.c
+++ b/em-format/e-mail-formatter-error.c
@@ -38,7 +38,6 @@ typedef struct _EMailFormatterErrorClass {
 } EMailFormatterErrorClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterError,
@@ -46,9 +45,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init));
 
@@ -139,18 +135,13 @@ e_mail_formatter_error_class_init (EMailFormatterErrorClass *class)
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_error_format;
 	iface->get_display_name = emfe_error_get_display_name;
 	iface->get_description = emfe_error_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_error_init (EMailFormatterError *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-extension.c b/em-format/e-mail-formatter-extension.c
index 381855bac5..3e10aa1488 100644
--- a/em-format/e-mail-formatter-extension.c
+++ b/em-format/e-mail-formatter-extension.c
@@ -21,7 +21,7 @@
 G_DEFINE_INTERFACE (
 	EMailFormatterExtension,
 	e_mail_formatter_extension,
-	E_TYPE_MAIL_EXTENSION)
+	G_TYPE_OBJECT)
 
 /**
  * EMailFormatterExtension:
diff --git a/em-format/e-mail-formatter-extension.h b/em-format/e-mail-formatter-extension.h
index e2c4ee6cf1..9a3f3925c4 100644
--- a/em-format/e-mail-formatter-extension.h
+++ b/em-format/e-mail-formatter-extension.h
@@ -19,7 +19,6 @@
 #ifndef E_MAIL_FORMATTER_EXTENSION_H
 #define E_MAIL_FORMATTER_EXTENSION_H
 
-#include <em-format/e-mail-extension.h>
 #include <em-format/e-mail-part.h>
 #include <em-format/e-mail-formatter.h>
 #include <camel/camel.h>
@@ -53,7 +52,12 @@ typedef struct _EMailFormatterExtension EMailFormatterExtension;
 typedef struct _EMailFormatterExtensionInterface EMailFormatterExtensionInterface;
 
 struct _EMailFormatterExtensionInterface {
-	EMailExtensionInterface	parent_interface;
+	GTypeInterface parent_interface;
+
+	/* This is a NULL-terminated array of supported MIME types.
+	 * The MIME types can be exact (e.g. "text/plain") or use a
+	 * wildcard (e.g. "text/ *"). */
+	const gchar **mime_types;
 
 	gboolean	(*format)	(EMailFormatterExtension *extension,
 					 EMailFormatter *formatter,
diff --git a/em-format/e-mail-formatter-headers.c b/em-format/e-mail-formatter-headers.c
index 5b62d5659d..855f6a6320 100644
--- a/em-format/e-mail-formatter-headers.c
+++ b/em-format/e-mail-formatter-headers.c
@@ -51,7 +51,6 @@ static const gchar *formatter_mime_types[] = {
 };
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterHeaders,
@@ -59,9 +58,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init))
 
@@ -594,18 +590,13 @@ e_mail_formatter_headers_class_init (EMailFormatterHeadersClass *class)
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_headers_format;
 	iface->get_display_name = emfe_headers_get_display_name;
 	iface->get_description = emfe_headers_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_headers_init (EMailFormatterHeaders *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-image.c b/em-format/e-mail-formatter-image.c
index 24ee2ef217..cd4d2e1e93 100644
--- a/em-format/e-mail-formatter-image.c
+++ b/em-format/e-mail-formatter-image.c
@@ -63,7 +63,6 @@ typedef struct _EMailFormatterImageClass {
 } EMailFormatterImageClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterImage,
@@ -71,9 +70,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init));
 
@@ -174,18 +170,13 @@ e_mail_formatter_image_class_init (EMailFormatterImageClass *class)
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_image_format;
 	iface->get_display_name = emfe_image_get_display_name;
 	iface->get_description = emfe_image_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_image_init (EMailFormatterImage *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-message-rfc822.c b/em-format/e-mail-formatter-message-rfc822.c
index f2d7d1cc66..dea737deb9 100644
--- a/em-format/e-mail-formatter-message-rfc822.c
+++ b/em-format/e-mail-formatter-message-rfc822.c
@@ -50,7 +50,6 @@ typedef struct _EMailFormatterMessageRFC822Class {
 } EMailFormatterMessageRFC822Class;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterMessageRFC822,
@@ -58,9 +57,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init));
 
@@ -265,18 +261,13 @@ e_mail_formatter_message_rfc822_class_init (EMailFormatterMessageRFC822Class *cl
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_message_rfc822_format;
 	iface->get_display_name = emfe_message_rfc822_get_display_name;
 	iface->get_description = emfe_message_rfc822_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_message_rfc822_init (EMailFormatterMessageRFC822 *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-print-headers.c b/em-format/e-mail-formatter-print-headers.c
index 2397f92308..1821268424 100644
--- a/em-format/e-mail-formatter-print-headers.c
+++ b/em-format/e-mail-formatter-print-headers.c
@@ -50,8 +50,6 @@ static const gchar *formatter_mime_types[] = {
 
 static void e_mail_formatter_print_formatter_extension_interface_init
 					(EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_print_mail_extension_interface_init
-					(EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterPrintHeaders,
@@ -59,9 +57,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_print_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_print_formatter_extension_interface_init))
 
@@ -243,18 +238,13 @@ e_mail_formatter_print_headers_class_init (EMailFormatterPrintHeadersClass *clas
 static void
 e_mail_formatter_print_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfpe_headers_format;
 	iface->get_display_name = emfpe_headers_get_display_name;
 	iface->get_description = emfpe_headers_get_description;
 }
 
 static void
-e_mail_formatter_print_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_print_headers_init (EMailFormatterPrintHeaders *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-quote-attachment.c b/em-format/e-mail-formatter-quote-attachment.c
index 8dff36af53..0dcf5f0206 100644
--- a/em-format/e-mail-formatter-quote-attachment.c
+++ b/em-format/e-mail-formatter-quote-attachment.c
@@ -42,7 +42,6 @@ typedef struct _EMailFormatterQuoteAttachmentClass {
 } EMailFormatterQuoteAttachmentClass;
 
 static void e_mail_formatter_quote_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterQuoteAttachment,
@@ -50,9 +49,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_quote_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_quote_formatter_extension_interface_init)
 )
@@ -143,18 +139,13 @@ e_mail_formatter_quote_attachment_class_init (EMailFormatterQuoteAttachmentClass
 static void
 e_mail_formatter_quote_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfqe_attachment_format;
 	iface->get_display_name = emfqe_attachment_get_display_name;
 	iface->get_description = emfqe_attachment_get_description;
 }
 
 static void
-e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_quote_attachment_init (EMailFormatterQuoteAttachment *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-quote-headers.c b/em-format/e-mail-formatter-quote-headers.c
index 368245c931..3f059dc1bb 100644
--- a/em-format/e-mail-formatter-quote-headers.c
+++ b/em-format/e-mail-formatter-quote-headers.c
@@ -45,8 +45,6 @@ typedef struct _EMailFormatterQuoteHeadersClass {
 
 static void e_mail_formatter_quote_formatter_extension_interface_init
 					(EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_quote_mail_extension_interface_init
-					(EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterQuoteHeaders,
@@ -54,9 +52,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_quote_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_quote_formatter_extension_interface_init))
 
@@ -269,18 +264,13 @@ e_mail_formatter_quote_headers_class_init (EMailFormatterQuoteHeadersClass *clas
 static void
 e_mail_formatter_quote_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emqfe_headers_format;
 	iface->get_display_name = emqfe_headers_get_display_name;
 	iface->get_description = emqfe_headers_get_description;
 }
 
 static void
-e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_quote_headers_init (EMailFormatterQuoteHeaders *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-quote-message-rfc822.c b/em-format/e-mail-formatter-quote-message-rfc822.c
index d1b5ae5b68..19f77c0792 100644
--- a/em-format/e-mail-formatter-quote-message-rfc822.c
+++ b/em-format/e-mail-formatter-quote-message-rfc822.c
@@ -44,7 +44,6 @@ typedef struct _EMailFormatterQuoteMessageRFC822Class {
 } EMailFormatterQuoteMessageRFC822Class;
 
 static void e_mail_formatter_quote_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterQuoteMessageRFC822,
@@ -52,9 +51,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_quote_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_quote_formatter_extension_interface_init));
 
@@ -171,18 +167,13 @@ e_mail_formatter_quote_message_rfc822_class_init (EMailFormatterQuoteMessageRFC8
 static void
 e_mail_formatter_quote_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfqe_message_rfc822_format;
 	iface->get_display_name = emfqe_message_rfc822_get_display_name;
 	iface->get_description = emfqe_message_rfc822_get_description;
 }
 
 static void
-e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_quote_message_rfc822_init (EMailFormatterQuoteMessageRFC822 *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-quote-text-enriched.c b/em-format/e-mail-formatter-quote-text-enriched.c
index 68d19ab633..ba991db2f4 100644
--- a/em-format/e-mail-formatter-quote-text-enriched.c
+++ b/em-format/e-mail-formatter-quote-text-enriched.c
@@ -40,8 +40,6 @@ typedef struct _EMailFormatterQuoteTextEnrichedClass {
 
 static void e_mail_formatter_quote_formatter_extension_interace_init
 					(EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_quote_mail_extension_interface_init
-					(EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterQuoteTextEnriched,
@@ -49,9 +47,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_quote_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_quote_formatter_extension_interace_init));
 
@@ -118,18 +113,13 @@ e_mail_formatter_quote_text_enriched_class_init (EMailFormatterQuoteTextEnriched
 static void
 e_mail_formatter_quote_formatter_extension_interace_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emqfe_text_enriched_format;
 	iface->get_display_name = emqfe_text_enriched_get_display_name;
 	iface->get_description = emqfe_text_enriched_get_description;
 }
 
 static void
-e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_quote_text_enriched_init (EMailFormatterQuoteTextEnriched *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-quote-text-html.c b/em-format/e-mail-formatter-quote-text-html.c
index d592150c28..bbc81905a1 100644
--- a/em-format/e-mail-formatter-quote-text-html.c
+++ b/em-format/e-mail-formatter-quote-text-html.c
@@ -43,8 +43,6 @@ typedef struct _EMailFormatterQuoteTextHTMLClass {
 
 static void e_mail_formatter_quote_formatter_extension_interface_init
 					(EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_quote_mail_extension_interface_init
-					(EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterQuoteTextHTML,
@@ -52,9 +50,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_quote_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_quote_formatter_extension_interface_init));
 
@@ -121,18 +116,13 @@ e_mail_formatter_quote_text_html_class_init (EMailFormatterQuoteTextHTMLClass *c
 static void
 e_mail_formatter_quote_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emqfe_text_html_format;
 	iface->get_display_name = emqfe_text_html_get_display_name;
 	iface->get_description = emqfe_text_html_get_description;
 }
 
 static void
-e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_quote_text_html_init (EMailFormatterQuoteTextHTML *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-quote-text-plain.c b/em-format/e-mail-formatter-quote-text-plain.c
index 584c6d1aeb..7deb9ebb75 100644
--- a/em-format/e-mail-formatter-quote-text-plain.c
+++ b/em-format/e-mail-formatter-quote-text-plain.c
@@ -41,8 +41,6 @@ typedef struct _EMailFormatterQuoteTextPlainClass {
 
 static void e_mail_formatter_quote_formatter_extension_interface_init
 					(EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_quote_mail_extension_interface_init
-					(EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterQuoteTextPlain,
@@ -50,9 +48,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_quote_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_quote_formatter_extension_interface_init));
 
@@ -140,18 +135,13 @@ e_mail_formatter_quote_text_plain_class_init (EMailFormatterQuoteTextPlainClass
 static void
 e_mail_formatter_quote_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emqfe_text_plain_format;
 	iface->get_display_name = emqfe_text_plain_get_display_name;
 	iface->get_description = emqfe_text_plain_get_description;
 }
 
 static void
-e_mail_formatter_quote_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_quote_text_plain_init (EMailFormatterQuoteTextPlain *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-secure-button.c b/em-format/e-mail-formatter-secure-button.c
index 6c41467c7c..b31c6fb819 100644
--- a/em-format/e-mail-formatter-secure-button.c
+++ b/em-format/e-mail-formatter-secure-button.c
@@ -43,7 +43,6 @@ typedef struct _EMailFormatterSecureButtonClass {
 } EMailFormatterSecureButtonClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterSecureButton,
@@ -51,9 +50,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init));
 
@@ -494,6 +490,7 @@ e_mail_formatter_secure_button_class_init (EMailFormatterSecureButtonClass *clas
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_secure_button_format;
 	iface->get_widget = emfe_secure_button_get_widget;
 	iface->get_display_name = emfe_secure_button_get_display_name;
@@ -501,12 +498,6 @@ e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInte
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_secure_button_init (EMailFormatterSecureButton *extension)
 {
 
diff --git a/em-format/e-mail-formatter-source.c b/em-format/e-mail-formatter-source.c
index becf1a81b5..ce9fc36957 100644
--- a/em-format/e-mail-formatter-source.c
+++ b/em-format/e-mail-formatter-source.c
@@ -39,7 +39,6 @@ typedef struct _EMailFormatterSourceClass {
 } EMailFormatterSourceClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterSource,
@@ -47,9 +46,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init)
 )
@@ -157,18 +153,13 @@ e_mail_formatter_source_class_init (EMailFormatterSourceClass *class)
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_source_format;
 	iface->get_display_name = emfe_source_get_display_name;
 	iface->get_description = emfe_source_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_source_init (EMailFormatterSource *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-text-enriched.c b/em-format/e-mail-formatter-text-enriched.c
index ca24c354dd..7a358bdfad 100644
--- a/em-format/e-mail-formatter-text-enriched.c
+++ b/em-format/e-mail-formatter-text-enriched.c
@@ -45,7 +45,6 @@ typedef struct _EMailFormatterTextEnrichedClass {
 } EMailFormatterTextEnrichedClass;
 
 static void e_mail_formatter_formatter_extension_interace_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterTextEnriched,
@@ -53,9 +52,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interace_init));
 
@@ -132,19 +128,13 @@ e_mail_formatter_text_enriched_class_init (EMailFormatterTextEnrichedClass *clas
 static void
 e_mail_formatter_formatter_extension_interace_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_text_enriched_format;
 	iface->get_display_name = emfe_text_enriched_get_display_name;
 	iface->get_description = emfe_text_enriched_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_text_enriched_init (EMailFormatterTextEnriched *formatter)
 {
-
 }
diff --git a/em-format/e-mail-formatter-text-html.c b/em-format/e-mail-formatter-text-html.c
index 838de92a92..08c40127d0 100644
--- a/em-format/e-mail-formatter-text-html.c
+++ b/em-format/e-mail-formatter-text-html.c
@@ -48,7 +48,6 @@ typedef struct _EMailFormatterTextHTMLClass {
 } EMailFormatterTextHTMLClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterTextHTML,
@@ -56,9 +55,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init));
 
@@ -371,18 +367,13 @@ e_mail_formatter_text_html_class_init (EMailFormatterTextHTMLClass *class)
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_text_html_format;
 	iface->get_display_name = emfe_text_html_get_display_name;
 	iface->get_description = emfe_text_html_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_text_html_init (EMailFormatterTextHTML *formatter)
 {
 
diff --git a/em-format/e-mail-formatter-text-plain.c b/em-format/e-mail-formatter-text-plain.c
index 4fc01187ce..ce620016a7 100644
--- a/em-format/e-mail-formatter-text-plain.c
+++ b/em-format/e-mail-formatter-text-plain.c
@@ -48,7 +48,6 @@ typedef struct _EMailFormatterTextPlainClass {
 } EMailFormatterTextPlainClass;
 
 static void e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface);
-static void e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailFormatterTextPlain,
@@ -56,9 +55,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_formatter_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_FORMATTER_EXTENSION,
 		e_mail_formatter_formatter_extension_interface_init));
 
@@ -206,18 +202,13 @@ e_mail_formatter_text_plain_class_init (EMailFormatterTextPlainClass *class)
 static void
 e_mail_formatter_formatter_extension_interface_init (EMailFormatterExtensionInterface *iface)
 {
+	iface->mime_types = formatter_mime_types;
 	iface->format = emfe_text_plain_format;
 	iface->get_display_name = emfe_text_plain_get_display_name;
 	iface->get_description = emfe_text_plain_get_description;
 }
 
 static void
-e_mail_formatter_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = formatter_mime_types;
-}
-
-static void
 e_mail_formatter_text_plain_init (EMailFormatterTextPlain *formatter)
 {
 
diff --git a/em-format/e-mail-parser-application-mbox.c b/em-format/e-mail-parser-application-mbox.c
index d7b41b0c86..2821e981de 100644
--- a/em-format/e-mail-parser-application-mbox.c
+++ b/em-format/e-mail-parser-application-mbox.c
@@ -43,7 +43,6 @@ typedef struct _EMailParserApplicationMBoxClass {
 } EMailParserApplicationMBoxClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserApplicationMBox,
@@ -51,9 +50,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -190,17 +186,12 @@ e_mail_parser_application_mbox_class_init (EMailParserApplicationMBoxClass *clas
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *interface)
 {
+	interface->mime_types = parser_mime_types;
 	interface->parse = empe_app_mbox_parse;
 	interface->get_flags = empe_app_mbox_get_flags;
 }
 
 static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *interface)
-{
-	interface->mime_types = parser_mime_types;
-}
-
-static void
 e_mail_parser_application_mbox_init (EMailParserApplicationMBox *self)
 {
 }
diff --git a/em-format/e-mail-parser-application-smime.c b/em-format/e-mail-parser-application-smime.c
index ba47fdf736..e5eab1bc4d 100644
--- a/em-format/e-mail-parser-application-smime.c
+++ b/em-format/e-mail-parser-application-smime.c
@@ -43,7 +43,6 @@ typedef struct _EMailParserAppplicationSMIMEClass {
 } EMailParserApplicationSMIMEClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserApplicationSMIME,
@@ -51,9 +50,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -179,17 +175,12 @@ e_mail_parser_application_smime_class_init (EMailParserApplicationSMIMEClass *cl
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *interface)
 {
+	interface->mime_types = parser_mime_types;
 	interface->parse = empe_app_smime_parse;
 	interface->get_flags = empe_app_smime_get_flags;
 }
 
 static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *interface)
-{
-	interface->mime_types = parser_mime_types;
-}
-
-static void
 e_mail_parser_application_smime_init (EMailParserApplicationSMIME *parser)
 {
 
diff --git a/em-format/e-mail-parser-attachment-bar.c b/em-format/e-mail-parser-attachment-bar.c
index a2b8ddd0be..77a796cae0 100644
--- a/em-format/e-mail-parser-attachment-bar.c
+++ b/em-format/e-mail-parser-attachment-bar.c
@@ -51,7 +51,6 @@ typedef struct _EMailParserAttachmentBarClass {
 } EMailParserAttachmentBarClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserAttachmentBar,
@@ -59,9 +58,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init))
 
@@ -103,13 +99,8 @@ e_mail_parser_attachment_bar_class_init (EMailParserAttachmentBarClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_attachment_bar_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_attachment_bar_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-extension.c b/em-format/e-mail-parser-extension.c
index df8fc54dcb..5497d3a1c6 100644
--- a/em-format/e-mail-parser-extension.c
+++ b/em-format/e-mail-parser-extension.c
@@ -23,7 +23,7 @@
 G_DEFINE_INTERFACE (
 	EMailParserExtension,
 	e_mail_parser_extension,
-	E_TYPE_MAIL_EXTENSION)
+	G_TYPE_OBJECT)
 
 static guint32
 mail_parser_extension_get_flags (EMailParserExtension *extension)
diff --git a/em-format/e-mail-parser-extension.h b/em-format/e-mail-parser-extension.h
index e5acece68e..06128cf68c 100644
--- a/em-format/e-mail-parser-extension.h
+++ b/em-format/e-mail-parser-extension.h
@@ -19,7 +19,6 @@
 #ifndef E_MAIL_PARSER_EXTENSION_H
 #define E_MAIL_PARSER_EXTENSION_H
 
-#include <em-format/e-mail-extension.h>
 #include <em-format/e-mail-parser.h>
 #include <camel/camel.h>
 
@@ -66,7 +65,12 @@ typedef enum {
 } EMailParserExtensionFlags;
 
 struct _EMailParserExtensionInterface {
-	EMailExtensionInterface	parent_interface;
+	GTypeInterface parent_interface;
+
+	/* This is a NULL-terminated array of supported MIME types.
+	 * The MIME types can be exact (e.g. "text/plain") or use a
+	 * wildcard (e.g. "text/ *"). */
+	const gchar **mime_types;
 
 	gboolean	(*parse)	(EMailParserExtension *extension,
 					 EMailParser *parser,
diff --git a/em-format/e-mail-parser-headers.c b/em-format/e-mail-parser-headers.c
index 366cedd4d2..e31f2932be 100644
--- a/em-format/e-mail-parser-headers.c
+++ b/em-format/e-mail-parser-headers.c
@@ -42,7 +42,6 @@ typedef struct _EMailParserHeadersClass {
 } EMailParserHeadersClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserHeaders,
@@ -50,9 +49,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -123,13 +119,8 @@ e_mail_parser_headers_class_init (EMailParserHeadersClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_headers_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_headers_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-image.c b/em-format/e-mail-parser-image.c
index d2ca8d69d0..18bc8ff208 100644
--- a/em-format/e-mail-parser-image.c
+++ b/em-format/e-mail-parser-image.c
@@ -39,7 +39,6 @@ typedef struct _EMailParserImageClass {
 } EMailParserImageClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserImage,
@@ -47,9 +46,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -127,13 +123,8 @@ e_mail_parser_image_class_init (EMailParserImageClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_image_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_image_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-inlinepgp-encrypted.c b/em-format/e-mail-parser-inlinepgp-encrypted.c
index 6a8ff8e1e1..081ba15dd8 100644
--- a/em-format/e-mail-parser-inlinepgp-encrypted.c
+++ b/em-format/e-mail-parser-inlinepgp-encrypted.c
@@ -41,7 +41,6 @@ typedef struct _EMailParserInlinePGPEncryptedClass {
 } EMailParserInlinePGPEncryptedClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserInlinePGPEncrypted,
@@ -49,9 +48,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -183,13 +179,8 @@ e_mail_parser_inline_pgp_encrypted_class_init (EMailParserInlinePGPEncryptedClas
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_inlinepgp_encrypted_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_inlinepgp_encrypted_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-inlinepgp-signed.c b/em-format/e-mail-parser-inlinepgp-signed.c
index dc8f4aa31f..c7a79b863f 100644
--- a/em-format/e-mail-parser-inlinepgp-signed.c
+++ b/em-format/e-mail-parser-inlinepgp-signed.c
@@ -41,7 +41,6 @@ typedef struct _EMailParserInlinePGPSignedClass {
 } EMailParserInlinePGPSignedClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserInlinePGPSigned,
@@ -49,9 +48,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -207,13 +203,8 @@ e_mail_parser_inline_pgp_signed_class_init (EMailParserInlinePGPSignedClass *cla
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_inlinepgp_signed_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_inlinepgp_signed_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-message-deliverystatus.c b/em-format/e-mail-parser-message-deliverystatus.c
index 6bec6e64ef..b7df31ec31 100644
--- a/em-format/e-mail-parser-message-deliverystatus.c
+++ b/em-format/e-mail-parser-message-deliverystatus.c
@@ -41,7 +41,6 @@ typedef struct _EMailParserMessageDeliveryStatusClass {
 } EMailParserMessageDeliveryStatusClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMessageDeliveryStatus,
@@ -49,9 +48,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -100,13 +96,8 @@ e_mail_parser_message_delivery_status_class_init (EMailParserMessageDeliveryStat
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_msg_deliverystatus_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_msg_deliverystatus_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-message-external.c b/em-format/e-mail-parser-message-external.c
index 79bbfd7247..c05ad0e6e4 100644
--- a/em-format/e-mail-parser-message-external.c
+++ b/em-format/e-mail-parser-message-external.c
@@ -41,7 +41,6 @@ typedef struct _EMailParserMessageExternalClass {
 } EMailParserMessageExternalClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMessageExternal,
@@ -49,9 +48,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -190,13 +186,8 @@ e_mail_parser_message_external_class_init (EMailParserMessageExternalClass *clas
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_msg_external_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_msg_external_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-message-rfc822.c b/em-format/e-mail-parser-message-rfc822.c
index 8ddf4806b9..ad50f59b49 100644
--- a/em-format/e-mail-parser-message-rfc822.c
+++ b/em-format/e-mail-parser-message-rfc822.c
@@ -44,7 +44,6 @@ typedef struct _EMailParserMessageRFC822Class {
 } EMailParserMessageRFC822Class;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMessageRFC822,
@@ -52,9 +51,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -153,17 +149,12 @@ e_mail_parser_message_rfc822_class_init (EMailParserMessageRFC822Class *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
+	iface->mime_types = parser_mime_types;
 	iface->parse = empe_msg_rfc822_parse;
 	iface->get_flags = empe_msg_rfc822_get_flags;
 }
 
 static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = parser_mime_types;
-}
-
-static void
 e_mail_parser_message_rfc822_init (EMailParserMessageRFC822 *parser)
 {
 
diff --git a/em-format/e-mail-parser-message.c b/em-format/e-mail-parser-message.c
index dcb9d998af..a4818392b5 100644
--- a/em-format/e-mail-parser-message.c
+++ b/em-format/e-mail-parser-message.c
@@ -43,7 +43,6 @@ typedef struct _EMailParserMessageClass {
 } EMailParserMessageClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMessage,
@@ -51,9 +50,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -120,13 +116,8 @@ e_mail_parser_message_class_init (EMailParserMessageClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_message_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_message_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-multipart-alternative.c b/em-format/e-mail-parser-multipart-alternative.c
index ca7fbddd57..cc06f41db4 100644
--- a/em-format/e-mail-parser-multipart-alternative.c
+++ b/em-format/e-mail-parser-multipart-alternative.c
@@ -40,7 +40,6 @@ typedef struct _EMailParserMultipartAlternativeClass {
 } EMailParserMultipartAlternativeClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMultipartAlternative,
@@ -48,9 +47,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -169,13 +165,8 @@ e_mail_parser_multipart_alternative_class_init (EMailParserMultipartAlternativeC
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_mp_alternative_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_mp_alternative_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-multipart-appledouble.c b/em-format/e-mail-parser-multipart-appledouble.c
index 08ea90faea..3f47280051 100644
--- a/em-format/e-mail-parser-multipart-appledouble.c
+++ b/em-format/e-mail-parser-multipart-appledouble.c
@@ -36,7 +36,6 @@ typedef struct _EMailParserMultipartAppleDoubleClass {
 } EMailParserMultipartAppleDoubleClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMultipartAppleDouble,
@@ -44,9 +43,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -107,13 +103,8 @@ e_mail_parser_multipart_apple_double_class_init (EMailParserMultipartAppleDouble
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_mp_appledouble_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_mp_appledouble_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-multipart-digest.c b/em-format/e-mail-parser-multipart-digest.c
index ed6a6daa63..7ca643d48a 100644
--- a/em-format/e-mail-parser-multipart-digest.c
+++ b/em-format/e-mail-parser-multipart-digest.c
@@ -39,7 +39,6 @@ typedef struct _EMailParserMultipartDigestClass {
 } EMailParserMultipartDigestClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMultipartDigest,
@@ -47,9 +46,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -146,17 +142,12 @@ e_mail_parser_multipart_digest_class_init (EMailParserMultipartDigestClass *clas
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
+	iface->mime_types = parser_mime_types;
 	iface->parse = empe_mp_digest_parse;
 	iface->get_flags = empe_mp_digest_get_flags;
 }
 
 static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = parser_mime_types;
-}
-
-static void
 e_mail_parser_multipart_digest_init (EMailParserMultipartDigest *parser)
 {
 
diff --git a/em-format/e-mail-parser-multipart-encrypted.c b/em-format/e-mail-parser-multipart-encrypted.c
index bae8de5166..05b192bcf4 100644
--- a/em-format/e-mail-parser-multipart-encrypted.c
+++ b/em-format/e-mail-parser-multipart-encrypted.c
@@ -39,7 +39,6 @@ typedef struct _EMailParserMultipartEncryptedClass {
 } EMailParserMultipartEncryptedClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMultipartEncrypted,
@@ -47,9 +46,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init))
 
@@ -193,13 +189,8 @@ e_mail_parser_multipart_encrypted_class_init (EMailParserMultipartEncryptedClass
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_mp_encrypted_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_mp_encrypted_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-multipart-mixed.c b/em-format/e-mail-parser-multipart-mixed.c
index 77feb71bcb..9127a51640 100644
--- a/em-format/e-mail-parser-multipart-mixed.c
+++ b/em-format/e-mail-parser-multipart-mixed.c
@@ -40,7 +40,6 @@ typedef struct _EMailParserMultipartMixedClass {
 } EMailParserMultipartMixedClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMultipartMixed,
@@ -48,9 +47,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -144,17 +140,12 @@ e_mail_parser_multipart_mixed_class_init (EMailParserMultipartMixedClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
+	iface->mime_types = parser_mime_types;
 	iface->parse = empe_mp_mixed_parse;
 	iface->get_flags = empe_mp_mixed_get_flags;
 }
 
 static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
-	iface->mime_types = parser_mime_types;
-}
-
-static void
 e_mail_parser_multipart_mixed_init (EMailParserMultipartMixed *parser)
 {
 }
diff --git a/em-format/e-mail-parser-multipart-related.c b/em-format/e-mail-parser-multipart-related.c
index f9e893f060..1fca09636c 100644
--- a/em-format/e-mail-parser-multipart-related.c
+++ b/em-format/e-mail-parser-multipart-related.c
@@ -40,7 +40,6 @@ typedef struct _EMailParserMultipartRelatedClass {
 } EMailParserMultipartRelatedClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMultipartRelated,
@@ -48,9 +47,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -138,13 +134,8 @@ e_mail_parser_multipart_related_class_init (EMailParserMultipartRelatedClass *cl
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_mp_related_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_mp_related_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-multipart-signed.c b/em-format/e-mail-parser-multipart-signed.c
index 45b29ff8aa..a57053f49e 100644
--- a/em-format/e-mail-parser-multipart-signed.c
+++ b/em-format/e-mail-parser-multipart-signed.c
@@ -39,7 +39,6 @@ typedef struct _EMailParserMultipartSignedClass {
 } EMailParserMultipartSignedClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserMultipartSigned,
@@ -47,9 +46,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -227,13 +223,8 @@ e_mail_parser_multipart_signed_class_init (EMailParserMultipartSignedClass *clas
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_mp_signed_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_mp_signed_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-secure-button.c b/em-format/e-mail-parser-secure-button.c
index 4f49dd99a0..ca38021388 100644
--- a/em-format/e-mail-parser-secure-button.c
+++ b/em-format/e-mail-parser-secure-button.c
@@ -38,7 +38,6 @@ typedef struct _EMailParserSecureButtonClass {
 } EMailParserSecureButtonClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserSecureButton,
@@ -46,9 +45,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init))
 
@@ -87,13 +83,8 @@ e_mail_parser_secure_button_class_init (EMailParserSecureButtonClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_secure_button_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_secure_button_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-source.c b/em-format/e-mail-parser-source.c
index ce22b0805b..1aef5fc074 100644
--- a/em-format/e-mail-parser-source.c
+++ b/em-format/e-mail-parser-source.c
@@ -38,7 +38,6 @@ typedef struct _EMailParserSourceClass {
 } EMailParserSourceClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserSource,
@@ -46,9 +45,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -88,13 +84,8 @@ e_mail_parser_source_class_init (EMailParserSourceClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_source_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_source_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-text-enriched.c b/em-format/e-mail-parser-text-enriched.c
index 503176ff6c..b666704625 100644
--- a/em-format/e-mail-parser-text-enriched.c
+++ b/em-format/e-mail-parser-text-enriched.c
@@ -39,7 +39,6 @@ typedef struct _EMailParserTextEnrichedClass {
 } EMailParserTextEnrichedClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserTextEnriched,
@@ -47,9 +46,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -108,13 +104,8 @@ e_mail_parser_text_enriched_class_init (EMailParserTextEnrichedClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_text_enriched_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_text_enriched_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-text-html.c b/em-format/e-mail-parser-text-html.c
index 98f359e573..5edce60f8a 100644
--- a/em-format/e-mail-parser-text-html.c
+++ b/em-format/e-mail-parser-text-html.c
@@ -41,7 +41,6 @@ typedef struct _EMailParserTextHTMLClass {
 } EMailParserTextHTMLClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserTextHTML,
@@ -49,9 +48,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -119,13 +115,8 @@ e_mail_parser_text_html_class_init (EMailParserTextHTMLClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_text_html_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_text_html_parse;
 }
 
 static void
diff --git a/em-format/e-mail-parser-text-plain.c b/em-format/e-mail-parser-text-plain.c
index 0ed85c2806..3d79901f5a 100644
--- a/em-format/e-mail-parser-text-plain.c
+++ b/em-format/e-mail-parser-text-plain.c
@@ -41,7 +41,6 @@ typedef struct _EMailParserTextPlainClass {
 } EMailParserTextPlainClass;
 
 static void e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface);
-static void e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface);
 
 G_DEFINE_TYPE_EXTENDED (
 	EMailParserTextPlain,
@@ -49,9 +48,6 @@ G_DEFINE_TYPE_EXTENDED (
 	G_TYPE_OBJECT,
 	0,
 	G_IMPLEMENT_INTERFACE (
-		E_TYPE_MAIL_EXTENSION,
-		e_mail_parser_mail_extension_interface_init)
-	G_IMPLEMENT_INTERFACE (
 		E_TYPE_MAIL_PARSER_EXTENSION,
 		e_mail_parser_parser_extension_interface_init));
 
@@ -246,13 +242,8 @@ e_mail_parser_text_plain_class_init (EMailParserTextPlainClass *class)
 static void
 e_mail_parser_parser_extension_interface_init (EMailParserExtensionInterface *iface)
 {
-	iface->parse = empe_text_plain_parse;
-}
-
-static void
-e_mail_parser_mail_extension_interface_init (EMailExtensionInterface *iface)
-{
 	iface->mime_types = parser_mime_types;
+	iface->parse = empe_text_plain_parse;
 }
 
 static void