I’ve just migrated a couple of servers from Courier-IMAP to Dovecot, and am very happy with the latter so far. I thought I’d share the courier2dovecot shell script I whipped together (based on the instructions I found in the migration
cyrus2courier is a nice little tool to convert a single mailbox from Cyrus-Imap into the Maildir++ format used by the Courier-Imap and Dovecot IMAP servers.