Re: [ietf-smtp] ALPN
Ned Freed <ned.freed@mrochek.com> Fri, 30 July 2021 14:05 UTC
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Cc: ietf-smtp@ietf.org
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Date: Fri, 30 Jul 2021 06:56:57 -0700
From: Ned Freed <ned.freed@mrochek.com>
In-reply-to: "Your message dated Fri, 30 Jul 2021 00:46:09 -0400" <YQOEEZ1JuOBzTap5@straasha.imrryr.org>
References: <20210729070230.GA30507@kiel.esmtp.org> <20210729185712.CEE1A254C9C0@ary.qy> <YQOEEZ1JuOBzTap5@straasha.imrryr.org>
To: Viktor Dukhovni <ietf-dane@dukhovni.org>
Archived-At: <https://mailarchive.ietf.org/arch/msg/ietf-smtp/ujrJOLWTBKxlwqMWwP_Y4cRR8VI>
Subject: Re: [ietf-smtp] ALPN
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> On Thu, Jul 29, 2021 at 02:57:12PM -0400, John Levine wrote: > > >Since there are already IDs for IMAP and POP3, it seems we are down to > > >3 (+SMTP) or 4 (+SUBMIT) unless we want to break existing applications? > I'd prefer to see "SUBMIT" as a separate ALPN value from "SMTP". As would I. A clean separation is always a good idea. > > Given that clients often don't know whether they're talking to an SMTP or a submission > > server, > In fact they almost always do, because "SUBMIT" generally requires > authentication, and SMTP relay does not, and the separate ports also > help. > > and servers don't know which one they are or maybe both, one ALPN would be plenty. > Submission servers are explicitly configured to accept outbound mail, > and it has been best practice for quite some time to not implement > submission on port 25, leaving that to 587, and more recently also 465. > > It's still pretty common for a server to offer SMTP on port 25, which > > turns into submission if the client authenticates. > This is a no longer recommended and diminishing practice. > - An MUA can always use the "SUBMIT" ALPN value. > - An occasional MTA that is configured to relay outbound mail > via a submission server, and has been updated to use ALPN, > can be configured to use "SUBMIT" when appropriate. I also don't see how this practice, which I agree is diminishing, is especially relevant to ALPN assignment. If you really want to do this in an ALPN context - I have no idea why - you can always use the SMTP ALPN to do it. Ned
- [ietf-smtp] ALPN Jeremy Harris
- Re: [ietf-smtp] ALPN John Levine
- Re: [ietf-smtp] ALPN Viktor Dukhovni
- Re: [ietf-smtp] ALPN Claus Assmann
- Re: [ietf-smtp] ALPN John Levine
- Re: [ietf-smtp] ALPN Alexey Melnikov
- Re: [ietf-smtp] ALPN Jeremy Harris
- Re: [ietf-smtp] ALPN Claus Assmann
- Re: [ietf-smtp] ALPN John R Levine
- Re: [ietf-smtp] ALPN John Levine
- Re: [ietf-smtp] ALPN Claus Assmann
- Re: [ietf-smtp] ALPN Arnt Gulbrandsen
- Re: [ietf-smtp] ALPN Claus Assmann
- Re: [ietf-smtp] ALPN John Levine
- Re: [ietf-smtp] ALPN Viktor Dukhovni
- Re: [ietf-smtp] ALPN Ned Freed