[Mailman-Users] Problem with listheaders

[Christian Schoepplein]

Hi!

I've a little problem with my listheaders. I don't know why, but for 
example the snederentry aon my site looks like this:

Sender: tmod-bounces at as-2.de

The same entry for this list looks different:

Sender: mailman-users-bounces+mail=schoeppi.net at python.org

What is responsible for the differenze? Is this a mailman or a MTA 
problem? I'm using mailman 2.1.2 and postfix 2.0.12.

Best regards,
Schoeppi