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Re: [ietf-smtp] Is this a valid Message-ID header ?

2020-03-05 03:18:58
On 05/03/2020 04:34, John Levine wrote:
I read IETF mailing lists on the IETF's IMAP server* and of late I've been
seeing some awfully funky stuff.

This is an actual Message-ID header in one of the messages in dnsop.
Is that valid?  Even though the MIME decodes to a an ASCII message ID
in the <string@domain> format, I think the answer is no.  That's not
what RFC 5322 sec 3.6 allows.

Message-ID: =?utf-8?q?=3CBN7PR11MB25474DF04998FF3AA9E0B80BC9E40=40BN7PR11MB2?= 

I would say, no, it's not valid.

The MIME encoding of headers is meant to sit on top of RFC 5322. So, format rules in RFC 5322 still have to apply BEFORE decoding the headers.


From: =?utf-8?q?B=C3=B3b Smith?= <bob(_at_)example(_dot_)com>

is valid, because that matches the RFC 5322 rules even though, without the MIME decoding, it's slightly gibberish. The format is still valid.


From: =?utf-8?q?B=C3=B3b Smith =3Cbob(_at_)example(_dot_)com=3E?=

is not valid, because it doesn't match the rules, even though the MIME decoded headers will be identical.


Paul Smith Computer Services
Tel: 01484 855800
Vat No: GB 685 6987 53

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