In the open source email world there seem to be two main competitors: Courier-MTA and Dovecot. These programs would sit on the email server and store messages for accounts that are destined for your domain. In a recent review of the email systems used where I work it’s been questioned as to whether Courier should still be used.
Slow to load in Squirrel mail
Squirrel mail is a popular open source webmail client written in PHP. It isn’t the prettiest web mail client on down the road but it is the most widely compatible. When inboxes are loaded with large amounts of emails in them, Squirrel mail takes a small ice age to load. This seems to be because Courier doesn’t index the maildir where the mail is stored, so every time you open up the webmail client it has to reaload the entire inbox.
Ongoing Auto responder problems
Problems with our auto responders have been getting progressively worse in Courier. It seems that due to the load of the system (partly down to the first Courier fault I mentioned: lack of indexing) doesn’t always manage to process the request to send an auto responder.
Dovecot is supposedly much faster than Courier due to the indexing it provides. Claims are that it is still not yet as feature rich as courier, but that it is certainly becoming more main stream. One big advantage of Dovecot is its sane use of configuration files, whereas Courier tends to spread them all over the system. Additionally Dovecot uses maildir format so is compatible with standard Courier installations.