Evgeniy Berdnikov via Exim-users wrote on 19.11.2021 09:16:
>>> Yes, "References:" has 1018 octets while RFC limit is 998.
>>> This is known bug for several Outlook versions.
>>>
>>>> Not sure how to mitigate this one. Maybe I should truncate/remove the
>>>> header - and possibly break the thread?
>>>
>>> Better solution is to fold this header (split over multiple lines).
>>
>> How do I achieve that with exim-4.95? Config option??
>
> There are several variants to try:
>
> 1. Use header add/remove directives in ACLs and/or routers to "reinstall"
> problematic "References:" header if its length is too high, in hope
> Exim would fold it correctly.
Exim doesn't fold such headers correctly.
> 2. Use transport filters (ch.24) on delivery stage.
Even if the transport filters correctly fold the headers, the
max_received_linelength variable will not be recalculated and may still
be greater than message_linelength_limit.
And the error "message has lines too long for transport" will still occur.
This error will occur even if a very long header is removed.
> 3. Route all incoming mails through external filter (such as Amavis),
> it should reformat broken mails and re-inject them back.
>
> I use variations of N3 with custom scripts, those configuraions are
> complex and they can't be reduced to a single config option.
>
> I have no experience with N1 and N2... Just try, it's interesting
> are they working variants or not.
>
> As ultimate solution, you can check for length of "References:" header
> and remove it if length is too long. This variant should always work.
>
--
Best wishes Victor Ustugov
mailto:victor@corvax.kiev.ua
JID: victor@???
public GnuPG/PGP key:
https://victor.corvax.kiev.ua/corvax.asc
