Re: [exim] message has lines too long for transport

On 2022-05-31 at 07:40:00 UTC-0400 (Tue, 31 May 2022 13:40:00 +0200)
Heiko Schlichting via Exim-users <exim-users@???>
is rumored to have said:

> I see the good intention of enforcing RFCs, but it should be limited
> to things that really make sense and not enforce otherworldly limits.

I generally agree with the principle.

> And to which - for good reason - no other software sticks.

That's actually a bit of an exaggeration.

Many MUAs (albeit not the most popular and modern ones) will adhere to
the 998 limit by using a transport encoding (QP or Base64) which create
shorter lines (of encoded text) or to use 'format=flowed' (RFC2646/3676)
rather than use the fundamentally broken model of
linebreak-per-paragraph text. Sendmail's default mailer flags include an
'auto-conversion' flag which happily re-encodes messages at delivery
time, breaking any DKIM signature that might be present. Postfix has 3
different line length limits, with the defaultb global limit being 2048
and the default limit for LMTP and SMTP clients (i.e. local and relayed
delivery) is 998. For a long time (through v2.8) it was 990.

There's a lesson somewhere in the fact that the solution for the root
problem was essentially solved with 'format=flowed' in 1999 and was
adopted by some MUAs then, only to be swamped by Microsoft ignoring it
and then Apple and Mozilla abandoning it so that their MUAs would be
more Outlook-like. 23 years later, we have threads on this list and the
Mailman2 list the same week full of frustration over the 'fixed'
problem.


--
Bill Cole
bill@??? or billcole@???
(AKA @grumpybozo and many *@billmail.scconsult.com addresses)
Not Currently Available For Hire