Postfix/dovecot mail not coming?

Question

postfix

Good afternoon forum users)
such a problem - mail does not come to the server from the outside and does not go between the boxes on this server.
centos7+postfix+dovecot is used,
this is what is seen in the logs when we send a letter from any server (yandex\mail\google\etc) to ours

Apr 28 00:56:39 140296-vds-admin postfix/smtpd[7861]: NOQUEUE: reject: RCPT from
forward12m.cmail.yandex.net[5.255.216.143]: 454 4.7.1 <[email protected]>: Relay access denied; from=<[email protected]> 
to=<[email protected]> proto=ESMTP helo=<forward12m.cmail.yandex.net>

it is not clear what kind of relay and why it is needed ... the mailer was not intended as a relay server.
when we send a letter between two mailboxes on this server, then in the logs this is


Apr 28 00:16:00 140296-vds-admin postfix/qmgr[16508]: 44D095D6DD: from=<[email protected]>, size=414, nrcpt=1 (queue active)
Apr 28 00:16:00 140296-vds-admin postfix/smtp[16870]: 44D095D6DD: to=<[email protected]>, relay=none, delay=0.16, 
delays=0.08/0.01/0.08/0, dsn=5.4.6, status=bounced (mail for noname.ru loops back to myself)

and outgoing works for everything except gmail.com, when we send it to it, it writes

Apr 28 04:26:24 140296-vds-admin postfix/smtp[29538]: F176C7C08C: to=<[email protected]>, relay=gmail-smtp-in.l.google.com[74.125.206.27]:25, delay=1.6, 
delays=0.43/0/0.46/0.71, dsn=5.7.1, status=bounced (host gmail-smtp-in.l.google.com[74.125.206.27] said: 550-5.7.1 [125.26.26.26      12] Our system has detected that this message is 550-5.7.1 likely 
unsolicited mail. To reduce the amount of spam sent to Gmail, 550-5.7.1 this message has been blocked. Please visit 550-5.7.1  https://support.google.com/mail/?p=UnsolicitedMessageError 550 
5.7.1  for more information. l69si4678775wrc.236 - gsmtp (in reply to end of DATA command))


Well, everything seems to be clear with the last one, we’ll figure it out, but I won’t even know what to do with the first two mistakes. what they just didn’t do, it’s useless 0.
I hope for you, the situation is a dead end, they googled everything but the problem was not solved.