If a woman ever tells a man size doesn’t matter, she’s certainly not being truthful.  Similarly anyone talking about packet sizes is also spinning a yarn.

Tunnels can and will reduce your MTU.  A lot of consumer NAT devices don’t handle/pass along the ICMP Unreachable codes packet-too-big and cant fragment correctly.  This means people end up ‘broken’ trying to access your site.  PMTU extensions can maybe help in some cases, but if the messages are getting dropped nothing will help.

We’ve been experiencing such a state/problem.  The most obvious place having an issue is the Comcast Mail Servers and the RoadRunner Mail Servers.  Individuals have also been experiencing it.

Worse we’ve had a hard time narrowing down the problem path.  Because it’s intermittent.

*sigh* Epic Failure.