Author: Florian Weimer Date: To: Marc Haber CC: exim-users Subject: Re: [exim] Receiving mail from outblaze and others times out after
initial 220
* Marc Haber:
> The host is behind a NAT router on a DSL line, so a MTU problem seems
> to be the kneejerk response, but neither the initial 220 greeting nor
> the HELO/EHLO from the remote site is likely to trip any MTU and PMTUD
> issues.
>
> Do you guys have an idea what could be the problem here?
The TCP implementation on the NAT router is probably broken. Maybe it
strips TCP options or something like that.
Unfortunately, without packet captures before and after the NAT
router, this is close to impossible to diagnose. You get what you pay
for. 8-(
