Upgrading vpopmail + courier to vpopmail + dovecot

First install dovecot with vpopmail support:

Ensure the vpopmail use flag is set for dovecot.

# emerge dovecot

Adjust the dovecot.conf file:

Uncomment and adjust the protocols line as appropriate:

protocols = imap imaps pop3 pop3s

Uncomment and adjust the first_valid_uid and last_valid_uid lines to match the vpopmail user id:

first_valid_uid = 89
last_valid_uid = 89

Comment out any existing userdb/passwd blocks.

Uncomment the passdb vpopmail line and the userdb vpopmail line.

Stop courier:

# /etc/init.d/courier-imap stop

Migrate IMAP subscription lists from courier format to dovecot format:

# wget http://www.dovecot.org/tools/courier-dovecot-migrate.pl
# for i in ~vpopmail/domains/*; do perl ./courier-dovecot-migrate.pl --to-dovecot --recursive $i; done

Start dovecot:

# /etc/init.d/dovecot start

Test that IMAP/POP3 is working ok.

Rejoice!

Remove courier from the run levels

# rc-update del courier-imapd default
# rc-update del courier-imapd-ssl default

Add dovecot

# rc-update add dovecot default

Remove courier

# emerge -C courier-imapd