Emails are not sent to gmail.com (postfix+dovecot) How to solve?

Question

gmail

Good day. Two days one mailbox spammed very strongly. All have been identified. We did all the tests of the mail server. Everything is set up as it should. All tests pass. But the error still remains. Mail is not sent to gmail, although it receives.
Spam started on the 15th, 16th, 17th. Treated. Since then, the post office has not been working. Searched the entire internet

mail opendkim # telnet gmail-smtp-in.l.google.com 25
Trying 64.233.161.27...
Connected to gmail-smtp-in.l.google.com.
Escape character is '^]'.
220 mx.google.com ESMTP m132-v6si2229344lfg.121 - gsmtp
HELO mx0.gb2bel.ru
250 mx.google.com at your service
MAIL from: <[email protected]>
250 2.1.0 OK m132-v6si2229344lfg.121 - gsmtp
RCPT to: <[email protected]>
250 2.1.5 OK m132-v6si2229344lfg.121 - gsmtp
DATA
354  Go ahead m132-v6si2229344lfg.121 - gsmtp
From: [email protected]
To: [email protected]
Subject: Test mail

TEST TEST
.
550-5.7.1 [XX.XX.XX.XX      19] Our system has detected that this message is
550-5.7.1 likely suspicious due to the very low reputation of the sending
550-5.7.1 domain. To best protect our users from spam, the message has been
550-5.7.1 blocked. Please visit
550 5.7.1  https://support.google.com/mail/answer/188131 for more information. m132-v6si2229344lfg.121 - gsmtp

Answer 1

so what did you rummaged through - is there an IP in the database of blacklists?
change or wait 6-9 months

Answer 2

Tidy up DNS records. Changed PTR from mx0.gb2bel.ru to gb2bel.ru
Swears on reputation all the same. =( I don't know what to do.