Can't send/receive email: connect to 127.0.0.1[127.0.0.1]:10024: Connection refused

Symptoms

• Sending and receiving mail fails with errors in /var/log/maillog

  CONFIG_TEXT: postfix/error[14359]: 3936F15A365: to=example@example.com, relay=none, delay=0.32, delays=0.32/0/0/0, dsn=4.4.1, status=deferred (delivery temporarily suspended: connect to 127.0.0.1[127.0.0.1]:10024: Connection refused)

  CONFIG_TEXT: Message: (!)_DIE: Suicide in child_init_hook: BDB can't connect db env. at /var/spool/amavisd/db: BDB0091 DB_VERSION_MISMATCH: Database environment version mismatch, Operation not permitted. at (eval 79) line 338.

• Amavis is up and running

  # systemctl status amavisd-new | grep Active
  Active: active (running) since Wed 2020-01-01 12:00:00 EST; 55min ago

Cause

Amavis (spam filter service) is stuck.

Resolution

1. Connect to the server via SSH

2. Restart the Amavis service:

   # systemctl restart amavisd-new

3. Re-send queued emails:

   # postsuper -r ALL