[Mailman-Users] group mismatch error with postfix

[Neven Luetic]

Hello,

when I send mail a mailinglist using mailman 2.1.5 and postfix 2.1.5 on
a debian sarge system I get:

Group mismatch error.  Mailman expected the mail
wrapper script to be executed as group "list", but
the system's mail server executed the mail script as
group "root".  Try tweaking the mail server to run the
script as group "list", or re-run configure, 
providing the command line option `--with-mail-gid=root'.

I read the FAQ, and the hints about file ownership of the mailman
aliases file in combination with postfix. It is set correctly to user
and owner "list" and 660:
-rw-rw----  1 list list 6,7K 2006-09-18 16:37 aliases
-rw-rw----  1 list list  12K 2006-09-18 16:37 aliases.db

Then I tried to install mailman from source giving --with-mail-gid=list
in case some other file is involved, but that didn't help either.

The wrapper-script has ownership root:list and guid bit set:
-rwxr-xr-x  1 root list 6,5K 2006-09-20 14:19 mailman

I just started using mailman, but I believe to have configured
everything as required by the documentation.

What else could be the problem?

Greetings 

Neven