Dear, I can not receive mails from gmail or other external boxes. Checking logs shows me this error. It is normal? because I am checking logs and I only see this.

Sep 23 08:34:18 exa20258-web-01 dovecot: master: Error: service(config): command startup failed, throttling for 2 secs Sep 23 08:34:23 exa20258-web-01 dovecot: config: Fatal: Error in configuration file /etc/dovecot/dovecot.conf line 111: Unknown setting: stmaster_address Sep 23 08:34:23 exa20258-web-01 dovecot: master: Error: service(config): command startup failed, throttling for 4 secs Sep 23 08:34:23 exa20258-web-01 dovecot: master: Warning: Killed with signal 15 (by pid=1 uid=0 code=kill) Sep 23 08:34:23 exa20258-web-01 dovecot: anvil: Warning: Killed with signal 15 (by pid=1 uid=0 code=kill) Sep 23 08:34:23 exa20258-web-01 dovecot: ssl-params: Warning: Killed with signal 15 (by pid=1 uid=0 code=kill) Sep 23 08:34:23 exa20258-web-01 dovecot: log: Warning: Killed with signal 15 (by pid=1 uid=0 code=kill) Sep 23 08:34:56 exa20258-web-01 dovecot: master: Dovecot v2.2.22 (fe789d2) starting up for imap, pop3, lmtp (core dumps disabled) Sep 23 08:41:28 exa20258-web-01 postfix/qmgr[17727]: 39246160389: from=<xxxx@gmail.com>, size=2622, nrcpt=1 (queue active) Sep 23 08:41:28 exa20258-web-01 dovecot: lmtp(14251): Fatal: Error reading configuration: Invalid settings: postmaster_address setting not given Sep 23 08:41:28 exa20258-web-01 postfix/lmtp[14250]: 39246160389: to=<xxxxx@latinclouds.com.ar>, relay=mail.latinclouds.com.ar[private/dovecot-lmtp], delay=13094, delays=13094/0.01/0.01/0, dsn=4.4.2, status=deferred (lost connection with mail.xxxx.com.ar[private/dovecot-lmtp] while receiving the initial server greeting)

Try reinstall and show this
-Mail Server is not currently installed, is it installed? Confirm
-Mail server is not initialized, is it initialized now?

Please try to re-install mailserver, Because the postfix must be version 3.x