Re: [exim] Error relaying large emails over two exim hosts

* OPTITAS Info:

> I did some investigation a few weeks ago and found out that after a
> while fragmented packets are sent over the Internet line. I tried
> some "optimized" MTU settings but could not solve the problem. I do
> not think it's a problem with the MTU.

It may be related to filtered ICMP packets. You should check what
fwbuilder does in this area.