Subject: [dispatch] Forced SMTP redirects

From: E Sam <[email-masked]>
Date: Thu, 9 Jul 2020 20:08:18 -0400

Hello everyone,

I have published a new internet-draft that might be of interest.

As always, its on the Datatracker:

https://datatracker.ietf.org/doc/draft-sam-smtp-redirects/

Some questions and thoughts for you:

Should 557 be a separate response code or should we just redefine 551?
I want to get your opinions.

Even if mail clients don't end up trying to reach the new address or
we end up making it so, it at least mandates the new replacement email
to be included in the response. This would clear up any ambiguity with
the existing 511 response code.

Anyway,

Let me know what you think! I think its a good idea, but some people
here might think otherwise. I plan on writing more email related
internet-drafts anyway. Just want to  see what people think.

There is the mail store WG but that seems like its geared more for
protocols like IMAP than SMTP, so I have put it in DISPATCH.

Obviously if there is something like a loop in redirects or an
excessively long redirect loop; the mail client should give up.

Note: as for the NNTP draft, I'll let my friend who is far more
knowledgeable in Usenet (he even has his own server) work on that one.

Have a good day!

---

From: "John Levine" <[email-masked]>
Date: 9 Jul 2020 21:59:47 -0400

I'd suggest reposting this to the ietf-smtp list where people who've
been around a lot longer than I have can explain why nobody implements
551 redirects (and as far as I can tell, nobody ever did) and there is
assigning a different response code won't change that. It may seem
like a good idea, but turns out not to work in practice.

FWIW I looked through the last seven months of my mail server's logs
and the total number of 551 responses is zero.

R's,
John

PS: There have been some attempts at setting up change-of-address
services where you can register old and new addresses, so mail servers
could query them after getting a 550, and they never went anywhere either.

See US Patents 6,654,789, 6,892,222, and 7,080,122.

On the other hand, a lot of mail systems now let users keep their
addresses after they leave, ranging from ISPs like Comcast and
Spectrum to universities who turn student addresses into alumni
addresses. They let you forward the mail, or you can add it to
the list of accounts your MUA checks, or either or both.