The postfix mail server is not receiving messages, what could be the problem?

Question

postfix

Mail is sent to all third-party boxes, I can not receive messages from both third-party and local. (it doesn’t reach itself either)
OS version Ubuntu 14.04.5 LTS
ISPmanager Lite 5.90.3

2 12:03:36 d-h dovecot: imap-login: Login: user=<[email protected]>, method=PLAIN, rip=54.242.172.178, lip=****, mpid=5594, TLS, session=<1R6XgDlkjgA28qyy>
Feb  2 12:03:39 d-h dovecot: imap([email protected]): Connection closed in=1543 out=3618
Feb  2 12:04:04 d-h dovecot: imap-login: Login: user=<[email protected]>, method=CRAM-MD5, rip=109.252.135.232, lip=****, mpid=5654, TLS, session=<3XNIgTlk/QBt/Ifo>
Feb  2 12:04:04 d-h dovecot: imap([email protected]): Disconnected: Logged out in=36 out=444
Feb  2 12:04:25 d-h postfix/qmgr[26153]: 14F794A034C1: from=<[email protected]>, size=664, nrcpt=1 (queue active)
Feb  2 12:04:25 d-h dovecot: lda([email protected]): Fatal: setgid(513(dp) from userdb lookup) failed with euid=109(dovecot), gid=1001(mgrsecure), egid=1001(mgrsecure): Operation not permitted (This binary should probably be called with process group set to 513(dp) instead of 1001(mgrsecure))
Feb  2 12:04:25 d-h dovecot: lda([email protected]): Fatal: setgid(513(dp) from userdb lookup) failed with euid=109(dovecot), gid=1001(mgrsecure), egid=1001(mgrsecure): Operation not permitted (This binary should probably be called with process group set to 513(dp) instead of 1001(mgrsecure))
Feb  2 12:04:25 d-hc dovecot: lda([email protected]): Fatal: setgid(513(dps) from userdb lookup) failed with euid=109(dovecot), gid=1001(mgrsecure), egid=1001(mgrsecure): Operation not permitted (This binary should probably be called with process group set to 513(dps) instead of 1001(mgrsecure))

Thank you!

Answer 1

show potfix logs

Answer 2

If I understand correctly, here it is.

2 12:49:00 d-hc postfix/smtpd[9680]: warning: ppp109-252-135-232.pppoe.spdop.ru[109.252.135.232]: SASL CRAM-MD5 authentication failed: Connection lost to authentication server
Feb  2 12:49:00 d-hc postfix/smtpd[9680]: 661904A043FF: client=ppp109-252-135-232.pppoe.spdop.ru[109.252.135.232], sasl_method=CRAM-MD5, [email protected]
Feb  2 12:49:00 d-hc postfix/cleanup[9607]: 661904A043FF: message-id=<[email protected]>
Feb  2 12:49:00 d-hc postfix/qmgr[26153]: 661904A043FF: from=<[email protected]>, size=669, nrcpt=1 (queue active)
Feb  2 12:49:00 d-hc postfix/pipe[9613]: 661904A043FF: to=<[email protected]>, relay=dovecot, delay=0.23, delays=0.17/0/0/0.05, dsn=4.3.0, status=deferred (temporary failure)

Answer 3

A banal question: is there free space or disk quotas for this user and/or for the server in general (in the partition with /var/mail)?