[TYPO3] Problems with this mallinglist

[Claus Bach]

I can write to this mallinglist by sending a mail to 
typo3-english at lists.netfielders.de like anybody else. When I get e-mail 
from the list, it says "reply to: typo3-english at lists.netfielders.de". 
When I do that I get an e-mail from "owner" whit the message "The 
message's content type was not explicitly allowed". Hope somebody can help ?

Claus Bach