I am trying to understand what the connecting client is doing in this situation on submission port 587. I replaced my domain with example.com.
Aug 18 14:15:27 mx postfix/smtpd[26495]: warning: hostname dsl-201-121-80-137-dyn.prod-infinitum.com.mx does not resolve to address 201.121.80.137: Name or service not known Aug 18 14:15:27 mx postfix/smtpd[26495]: connect from unknown[201.121.80.137] Aug 18 14:15:27 mx postfix/smtpd[26495]: NOQUEUE: reject: RCPT from unknown[201.121.80.137]: 554 5.7.1 <r99...@gmail.com>: Recipient address rejected: Access denied; from=<test...@example.com> to=<r99...@gmail.com> proto=ESMTP helo=<TDA1017C2> Aug 18 14:15:27 mx postfix/smtpd[26495]: lost connection after RCPT from unknown[201.121.80.137] Aug 18 14:15:27 mx postfix/smtpd[26495]: disconnect from unknown[201.121.80.137] ehlo=1 mail=1 rcpt=0/1 commands=2/3 Normally when someone is trying to guess submission logins i would see something like: warning: unknown[62.233.50.137]: SASL PLAIN authentication failed: Connection lost to authentication server What is the client doing in the first log to get "Recipient address rejected: Access denied;" The submission restrictions are: -o smtpd_sasl_type=dovecot -o smtpd_sasl_path=private/auth -o smtpd_sasl_auth_enable=yes -o smtpd_sasl_security_options=noanonymous -o smtpd_relay_restrictions=permit_sasl_authenticated,reject_unauth_destination -o smtpd_recipient_restrictions=reject_sender_login_mismatch,permit_sasl_authenticated,reject
