holger wrote:
> i don´t think this is a problem regarding the borderware mxtreme,
> because sometimes they get timeouts when they connect directly via
> telnet to our mailsevers port 25 (without the mxtreme)

This makes it sound like a networking packet/connectivity issue then,
rather than a MTA problem.

If it only happens with this one company and not others, then it's likely
a problem with networking on their end.