After migration from courier-IMAP service to Dovecot, mail is not getting delivered and
maillog is being flooded with:
sieve: failed to stat user's sieve script: stat failed: Permission denied
A step with correct permissions' setting was skipped in the deployment guide.
Set the permissions for
# chgrp qmail /usr/libexec/dovecot/deliver # chmod g+s /usr/libexec/dovecot/deliver # usermod -G qmail dovecot
As described in mail hosting deployment guide page 94.