On 20 Dec 2023 12:00 -0500, from poc...@columbus.rr.com (Pocket): > The SMTP server on bendel.debian.org should have resent? No?
In one word: No. Because the mail in question was rejected by the recipient MTA (pkvw-mx.msg.pkvw.co.charter.net) with a PERMANENT error. This is clearly shown in your message-ID <43410a14-1689-418a-8152-d734e3d81...@columbus.rr.com>. SMTP 5xx response codes are _permanent errors_. They indicate that the _sender_ needs to fix something about the message for delivery to be possible; the situation will not resolve itself. This has been specified since the original SMTP standard in 1982; see RFC 821 appendix E (page 48-49). https://www.rfc-editor.org/rfc/rfc821#page-48 In the current standard, the same thing is specified (using almost exactly the same wording, even) in RFC 5321 section 4.2.1. https://www.rfc-editor.org/rfc/rfc5321#section-4.2.1 If your ISP had done the right thing and rejected with a 4xx response, as is customary in for example overload conditions, then the sending MTA would have kept that message in its outbound queue and retried later, and we wouldn't have this long meta-discussion. If your ISP's mail servers can't even speak proper SMTP, please don't expect that everyone else on the Internet will bend over backwards to cater to a non-standard implementation. -- Michael Kjörling 🔗 https://michael.kjorling.se “Remember when, on the Internet, nobody cared that you were a dog?”
