Daniel,
Thanks for the reply. After reading up on that link, I removed all chroot settings, letting dovecot use its defaults. I figure that should open things up as much as possible for testing. My configuration now looks like this, but I get no change in behavior:
# 2.2.9: /etc/dovecot/dovecot.conf # OS: Linux 3.13.0-24-generic x86_64 Ubuntu 14.04 LTS ext4 auth_debug = yes auth_debug_passwords = yes auth_mechanisms = plain cram-md5 auth_verbose = yes base_dir = /var/run/dovecot/ disable_plaintext_auth = no info_log_path = /var/log/dovecot.info listen = * log_path = /var/log/dovecot log_timestamp = "%Y-%m-%d %H:%M:%S " mail_location = maildir:/home/vmail/%d/%n/Maildir passdb { args = /etc/dovecot/passwd driver = passwd-file } protocols = imap pop3 service auth { executable = /usr/lib/dovecot/auth unix_listener /var/spool/postfix/private/auth-client { group = postfix mode = 0666 user = postfix } unix_listener auth-userdb { group = postfix mode = 0777 user = postfix } user = vmail } service imap-login { executable = /usr/lib/dovecot/imap-login user = dovecot } service imap { executable = /usr/lib/dovecot/imap } service pop3-login { executable = /usr/lib/dovecot/pop3-login inet_listener pop3 { address = * port = 110 } inet_listener pop3s { address = * port = 995 } user = dovecot } service pop3 { executable = /usr/lib/dovecot/pop3 } ssl = required ssl_cert =