[Mailman-Users] Mailman problems

[VerenigdeStaten.Info]

Hi all,

We are running for several years a mailing list on www.verenigdestaten.info, 
Since november 7 mailman is recieving bounces from many email adresses. At 
this time 80% of our subscribers are bounced and disabled from the list. The 
bounced adresses are from several providers and the are, if mailed 
individual, completely working.

We did some research, but running out of options. Is there someone who 
regonize this problem or can help us out?

We checked our IP at spam cops, but we're not listed.

Thankz in advance....

Wop