On Mon, Nov 22, 2021, Aaron Poffenberger wrote: > some MTAs reject emails where fqdn of the Message-ID does not have a > reverse look-up, returning the error:
What do you mean by "reverse look-up" here? A FQDN might have an A/AAAA or MX record, not a PTR record. > <user>@*sbcglobal.net*: 550 5.7.1 Connections not accepted from > servers without a valid sender domain.alph758 Fix reverse DNS for <ip > address> "reverse DNS for <ip> address" sounds like a PTR entry for the client IP which is connecting to the server. I'm not sure the problem is really related to "fqdn of the Message-ID", could you give a real example: sending from the same host using the same addresses but two different Message-ID - only one of which fulfills the requirement you stated.
