[Mailman-Users] Error when using Postfix

[Trimble, Ronald D]

Everyone,
                I have come about as far as I can with my limited knowledge to get this application running.  I am getting the following error.  Can someone please tell me how to address it?

#< #5.0.0 X-Postfix; Command died with status 2: "/usr/local/mailman/mail/mailman post testlist". 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 "nobody". Try tweaking the mail server to run the script as group "mailman", or re-run configure, providing the command line option `--with-mail-gid=nobody'.> #SMTP#

Thanks,
Ron