Last login attempt from roundcube
Jan 29 16:38:08 ts130 dovecot: imap-login: Login: user=<tdukes>, method=PLAIN, rip=::1, lip=::1, mpid=2076, secured, session=<dVTVg0JHkAAAAAAAAAAAAAAAAAAAAAAB> Jan 29 16:38:08 ts130 dovecot: imap(tdukes): Error: user tdukes: Initialization failed: Namespace '': Mail storage autodetection failed with home=/home/tdukes Jan 29 16:38:08 ts130 dovecot: imap(tdukes): Error: Invalid user settings. Refer to server log for more information.
It's a dovecot configuration error. The login has clearly worked, so stop fussing with the firewall.
You need to look in /etc/dovecot/conf.d/10-mail.conf and set 'mail_location' to where the user's email is stored. If you are using Maildir then it will probably be
mail_location = maildir:~/Maildir
if mbox, then probably
mail_location = mbox:~/mail:INBOX=/var/mail/%u
but adjust the paths to where things are actually stored.
You will, obviously, have to set your MTA to deliver the mail to the correct location and in the correct format as well.
P.