Re: [ietf-smtp] DSNs
Viktor Dukhovni <ietf-dane@dukhovni.org> Sat, 25 April 2020 18:48 UTC
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From: Viktor Dukhovni <ietf-dane@dukhovni.org>
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Subject: Re: [ietf-smtp] DSNs
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On Sat, Apr 25, 2020 at 07:56:56AM -0700, Dave Crocker wrote: > On 4/25/2020 6:01 AM, Ned Freed wrote: > > Aside from implementation errors, I've seen no operational problems with DSNs, > > only with the DSN extension. The problem there is that some people have > > claimed that since NOTIFY=SUCCESS is a part of the base and they don't want to > > do it the only alternative is to disable the entire extension. I disagree; I > > think that since security concerns are paramount it's perfectly OK to simply > > reject NOTIFY=SUCCESS on security grounds. > > Perhaps this goes to the challenge of a specification's distinguishing > its essential core, versus desired-but-not-required enhancements. > > Fail to support all of the core and it's not valid to claim to support > the specification. > > The danger of a pick-and-choose free-for-all is that a claim to support > a specification provides little useful information. I'm very much with Dave on this one. If you're not offering NOTIFY=SUCCESS, then you're not offering DSN. Pretending to support it, but then not offering it is breakage. On the other hand, since I ignore "DSN" on the outbound leg, I avoid running into any problems should the remote side misrepresent its behaviour. There is no mechanism to offer a fine-grained subset of the DSN ESMTP extension, so I turn it off entirely. The only one I'd be comfortable in offering to outsiders would be "NEVER", but the ability to avoid some rare bounces is not that compelling. Thus, for example, I also only send delay notices for outbound mail from inside, but not for inbound mail from outside. -- Viktor.
- [ietf-smtp] SMTP, DSNs, and enhanced replies (was… John C Klensin
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies … Hector Santos
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies … Dave Crocker
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies … Brandon Long
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies … John Levine
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies Dave Crocker
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies John R Levine
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies … Ned Freed
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies Ned Freed
- Re: [ietf-smtp] SMTP, DSNs, and enhanced replies Jeremy Harris
- Re: [ietf-smtp] DSNs Claus Assmann
- Re: [ietf-smtp] DSNs Viktor Dukhovni
- Re: [ietf-smtp] DSNs John Levine
- Re: [ietf-smtp] DSNs John C Klensin
- Re: [ietf-smtp] DSNs John Levine
- Re: [ietf-smtp] DSNs Alessandro Vesely
- Re: [ietf-smtp] DSNs Viktor Dukhovni
- Re: [ietf-smtp] DSNs Ned Freed
- Re: [ietf-smtp] DSNs Dave Crocker
- Re: [ietf-smtp] DSNs Viktor Dukhovni
- Re: [ietf-smtp] DSNs Dave Crocker
- Re: [ietf-smtp] DSNs Ned Freed
- Re: [ietf-smtp] DSNs Dave Crocker
- Re: [ietf-smtp] DSNs Jeremy Harris
- Re: [ietf-smtp] DSNs John C Klensin
- Re: [ietf-smtp] DSNs Scott Kitterman
- Re: [ietf-smtp] DSNs John C Klensin
- [ietf-smtp] Variable HELO name, was DSNs Alessandro Vesely
- Re: [ietf-smtp] DSNs Arnt Gulbrandsen
- Re: [ietf-smtp] Variable HELO name, was DSNs Ned Freed
- Re: [ietf-smtp] Variable HELO name, was DSNs John C Klensin
- Re: [ietf-smtp] DSNs John C Klensin
- Re: [ietf-smtp] DSNs Dave Crocker
- Re: [ietf-smtp] DSNs Ned Freed
- Re: [ietf-smtp] DSNs Viktor Dukhovni
- Re: [ietf-smtp] DSNs John Levine
- Re: [ietf-smtp] DSNs Sam Varshavchik
- Re: [ietf-smtp] DSNs Valdis Kl ē tnieks
- Re: [ietf-smtp] DSNs Scott Kitterman
- Re: [ietf-smtp] DSNs John Levine
- Re: [ietf-smtp] DSNs Sam Varshavchik
- Re: [ietf-smtp] DSNs Valdis Kl ē tnieks
- Re: [ietf-smtp] DSNs Laura Atkins
- Re: [ietf-smtp] DSNs Sam Varshavchik
- Re: [ietf-smtp] DSNs John Levine
- Re: [ietf-smtp] DSNs Sam Varshavchik
- Re: [ietf-smtp] DSNs John Levine
- Re: [ietf-smtp] DSNs Sam Varshavchik
- Re: [ietf-smtp] DSNs Ned Freed
- Re: [ietf-smtp] DSNs Viktor Dukhovni
- Re: [ietf-smtp] DSNs Sam Varshavchik