Mailman og Postfix

Jeg har kæmpe problemer.

Jeg kører med postfix som mail server derefter har jeg installeret ”MailMan” men jeg har et problem.

Jeg har oprettet en ”group mail” som hedder:

dudez@dudez.dk  den skal så sende ud til følgende bruger:

Bruger A
Bruger B
Bruger C

Men når mailen bliver sendt af sted skriver ”Postfix” tilbage:

Undelivered Mail Returned to Sender

This is the Postfix program at host indugw01.indu.adsl.dk.

I'm sorry to have to inform you that the message returned
below could not be delivered to one or more destinations.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the message returned below.

                        The Postfix program

<dudez@indugw01.indu.adsl.dk>: Command died with status 2:
    "/opt/mailman/mail/mailman post dudez". Command output: Group mismatch
    error.  Mailman expected the mail wrapper script to be executed as group
    "mailman", but the system's mail server executed the mail script as group
    "nogroup".  Try tweaking the mail server to run the script as group
    "mailman", or re-run configure,  providing the command line option
    `--with-mail-gid=nogroup'.


Please help.