*) Sorry, what does the "archive mail" mean? Is it just moving email to another IMAP folder?
*) Please turn on debug mode in Dovecot (POP3/IMAP server) first, then try to archive email with Outlook again, check whether there's any related error message in Dovecot log file (/var/log/dovecot.log and /var/log/sieve.log). Reference: http://www.iredmail.org/wiki/index.php? … In.Dovecot