On 2017-07-26 02:48, Rupert Gallagher wrote: > When a mail arrives without mid, either the sender did not use a real > SMTP server or tried to hide it. We have a custom SA rule for it. We > also reject upfront any mid with a syntax error, or whose domain does > not have a rdns (eg. @localhost.localdomain or @test.com).
I suspect you'll miss this message, then. My Message-IDs intentionally identify the originating host, which makes me more confident that they're unique. The originating host is behind two layers of NAT and DHCP, and naturally doesn't have rDNS. I don't know how to ensure uniqueness if I use the relaying SMTP server's domain, or the domain of the perimeter of the NATted network, which can have rDNS (and does, via a dyn-like update service), but which I do not own or control. -- Please don't Cc: me privately on mailing lists and Usenet, if you also post the followup to the list or newsgroup. Do obvious transformation on domain to reply privately _only_ on Usenet.
