After changing the interface addresses with 10.214.2.138 on 172.16.5.4 accepting mail from the outside.
NOQUEUE: reject: RCPT from unknown[46.29.XX.XX]: 450 4.7.1 Client host rejected: cannot find your hostname, [18.104.22.168]; from= to= proto=SMTP helo=
And from me outside the mail goes. DNS is configured. back area is. but the postfix is not resolved address. I do not understand why? is there somewhere else where you need to register the dns settings?