[Dovecot] Mail undeliverable error

[jan gestre]

Hi Guys,

I've already posted this to the postfix mailing list and they made
sure the error as the title suggest was generated by dovecot and not
the other way around. I have an almost perfectly working multi domain
mail server running dovecot+postfix+mysql+postfixadmin behind pfsense,
when we transferred office, issues arose, suddenly users using email
clients like thunderbird/outlook suddenly can't send mail when outside
the office and instead gets an smtp denied or worst a mail
undeliverable error. The mail undeliverable error was that the
postmaster user is unknown yet I've created the alias using
postfixadmin. I've made repeated test and sent mail directly to the
postmaster and the email was received by the intended user, I'm
stumped and have no idea to fix this.

Hope you can help me, TIA.

Here's the output of dovecot -n:

dovecot -n
# /etc/dovecot.conf
base_dir: /var/run/dovecot/
log_timestamp: %Y-%m-%d %H:%M:%S
ssl_cert_file: /etc/postfix/ssl/mail-cert.pem
ssl_key_file: /etc/postfix/ssl/mail-key.pem
login_dir: /var/run/dovecot//login
login_executable(default): /usr/libexec/dovecot/imap-login
login_executable(imap): /usr/libexec/dovecot/imap-login
login_executable(pop3): /usr/libexec/dovecot/pop3-login
first_valid_uid: 150
last_valid_uid: 150
mail_extra_groups: mail
mail_location: maildir:/home/virtualmail/%d/%u
maildir_copy_with_hardlinks: yes
mail_executable(default): /usr/libexec/dovecot/imap
mail_executable(imap): /usr/libexec/dovecot/imap
mail_executable(pop3): /usr/libexec/dovecot/pop3
mail_plugin_dir(default): /usr/lib/dovecot/imap
mail_plugin_dir(imap): /usr/lib/dovecot/imap
mail_plugin_dir(pop3): /usr/lib/dovecot/pop3
pop3_client_workarounds(default):
pop3_client_workarounds(imap):
pop3_client_workarounds(pop3): outlook-no-nuls oe-ns-eoh
auth default:
  mechanisms: plain login digest-md5
  user: nobody
  passdb:
    driver: sql
    args: /etc/dovecot-sql.conf
  userdb:
    driver: sql
    args: /etc/dovecot-sql.conf
  socket:
    type: listen
    client:
      path: /var/run/dovecot/auth-client
      mode: 432
      user: postfix
      group: mail
    master:
      path: /var/run/dovecot/auth-master
      mode: 432
      user: virtualmail
      group: mail