[Oberon] Duplicate headers in SMTP. Was RFC 5322 and ETH Oberon SMTP.

peter at easthope.ca peter at easthope.ca
Fri Jul 22 17:52:24 CEST 2022

>From schierlm at gmx.de  Fri Jul 15 19:22:23 2022
> As J?rg already suggested, look at the headers/content of the emails, ...

Here is another "Undelivered" reply from a gmail address.

> This is the mail system at host gateway20.websitewelcome.com. > ...
> <...... at gmail.com>: host gmail-smtp-in.l.google.com[] said: 
>     550-5.7.1 [] Our system has detected that this message is not 
>     RFC 550-5.7.1 5322 compliant: duplicate headers. To reduce the amount of 
>     spam sent 550-5.7.1 to Gmail, this message has been blocked. Please review 
>     550 5.7.1  RFC 5322 specifications for more information. 
>     l21-20020a170906939500b0072b460163d9si5427332ejx.196 - gsmtp (in reply to 
>     end of DATA command)

Note "5322 compliant: duplicate headers." These header fields were 
added by smarthost ccx.websitewelcome.com.

> X-AntiAbuse: This header was added to track abuse, please include it with any abuse report 
> X-AntiAbuse: Primary Hostname - ccx.websitewelcome.com 
> X-AntiAbuse: Original Domain - gmail.com 
> X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12]

RFC 5322 doesn't mention the X-AntiAbuse header.  It provides a syntax 
for folding a long header body.  One folded header is an alternative 
to the four X-AntiAbuse headers.

The table in 
https://datatracker.ietf.org/doc/html/rfc5322#section-3.6 Field Definitions 
allows unlimited repetition of some fields.  With no mention of the 
X-AntiAbuse field in the RFC, repetition should be OK.  Probably the 
MUA (the Oberon system here) can't prevent ccx.websitewelcome.com from 
adding the multiple headers.  

Refusal to accept a message because it contains a header meant to 
combat spam is perverse but beyond my influence.  

Failure of the message to mun.ca is entirely distinct. Blocking all 
messages from a prominent server because of "reputation" doesn't 
strike me as good practise but switching to another server may be the 
only feasible solution.

Regards,                           ... P.L.

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