Courier vs Dovecot

Courier -vs- Dovecot
Courier was the original IMAP server for use with the Mail Toaster. Courier has been a persistent nuisance to keep working reliably due to frequent changes. However, it works well, scales well, and is still a supported feature.

Then came Dovecot. It has been a small, fast, and extremely dependable POP3/IMAP server. It also builds much, much faster than Courier. I highly recommend Dovecot.

There are some known Migrating to Dovecot that should be reviewed prior to switching.

Courier IMAP

Sqwebmail

Dovecot