RTFM before configuring and running Courier!!! Check and/or modify the following configuration files to suit your needs: %%PREFIX%%/etc/courier/courierd %%PREFIX%%/etc/courier/esmtpd %%PREFIX%%/etc/courier/esmtpd-msa %%PREFIX%%/etc/courier/esmtpd-ssl %%WITHFAX%% %%PREFIX%%/etc/courier/faxcoverpage.tr %%WITHFAX%% %%PREFIX%%/etc/courier/faxnotifyrc %%WITHFAX%% %%PREFIX%%/etc/courier/faxrc %%PREFIX%%/etc/courier/imapd %%PREFIX%%/etc/courier/imapd-ssl %%PREFIX%%/etc/courier/ldapaddressbook %%WITHLDAP%% %%PREFIX%%/etc/courier/ldapaliasrc %%PREFIX%%/etc/courier/pop3d %%PREFIX%%/etc/courier/pop3d-ssl Do not forget to update /etc/pam.d/ or /etc/pam.conf with the contents of %%PREFIX%%/etc/courier/*.authpam. To enable Courier-MTA to start at boot time, set these variables in your /etc/rc.conf file: courier_enable="YES" sendmail_enable="NONE" Note: in newer OS versions you should change variables used in /etc/rc.conf file, as NONE for sendmail_enable is deprecated and will be not supported in future: courier_enable="YES" sendmail_enable="NO" sendmail_submit_enable="NO" sendmail_outbound_enable="NO" sendmail_msp_queue_enable="NO" Also, you will want to disable some Sendmail specific daily maintenance routines in your /etc/periodic.conf file: daily_clean_hoststat_enable="NO" daily_status_mail_rejects_enable="NO" daily_status_include_submit_mailq="NO" daily_submit_queuerun="NO" Documentation (if installed locally) is located in %%DOCSDIR%%/ otherwise see http://www.Courier-MTA.org/ If you are planning to serve shared maildirs, then you should create a cron job that runs at regular intervals (once every few hours is fine) that executes the following script to update the shared folder index: %%PREFIX%%/share/courier/sharedindexupdate