Cisco pix MTU problem, was RE: [Exim] Exchange, HELO and und…

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Szerző: Alan J. Flavell
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Címzett: Exim users list
Régi témák: RE: [Exim] Exchange, HELO and underscores
Tárgy: Cisco pix MTU problem, was RE: [Exim] Exchange, HELO and underscores
On Fri, 27 Jun 2003, Cory Daehn wrote:

> If enough of their mail bounces, they'll fix it.


That's easily said, but we're currently struggling with a different
problem (Cisco pix MTU munging) where we're being accused of being
the ONLY site that cannot send mail to them. So although there is
even documentary evidence that they are the ones at fault, they don't
seem interested in fixing it.

My point in posting here was really to address the general issue of
"if enough mail bounces, they'll fix it" - but if anyone knows a
really effective solution to this specific problem, we'd be interested
to have it. I'm sure I once found a page that showed how to set a
pessimistic MTU for all destinations, but such general breakage of
one's IP protocol stack isn't really an attractive approach.

Several previous threads on the mailing list have addressed this
problem ("timeout at data close" being the typical observed symptoms)
but I don't see a comfortable solution that could be applied by the
other party. I recently hypothesised that using /sbin/route to set a
host route with a specific MSS might do the trick - and funnily enough
it did seem to achieve the desired effect at the time, but we've been
unable to reproduce the success since.

> of those that says it's not the server's responsibility to scan mail for
> viruses, it's the client's responsibility, and anyone who doesn't use
> common sense and run a GOOD virus protection program and keep it up to
> date deserves what they get.


Yeah, but it's the innocent victims whose addresses get counterfeited
as sender - and the postmasters who have to field the flak from all
directions - who suffer the most. The actual perpetrators seem to
accept virus infestation as a normal part of life. "My peecee went
windows-up again", a casual remark that I overheard recently. So I'm
all for blocking such abuses at any point I can get my hand on the
lever.