[Mailman-Users] Group Mismatch error

[Myo Zaw Nyunt]

HI All,

I got the following error after I post my first mail to the list. I am using
Sendmail. I don't know what to do.

Regards,
Myo Gyi

Servername Mailman mail-wrapper: 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 "mailnull".  Try tweaking the mail
server to run the script as group "mailman", or re-run configure,  providing
the command line option `--with-mail-gid=mailnull'.

server1 sm-mta[624]: k0LDB3ZM000623: to="|/usr/local/mailman/mail/mailman
post
test"\r, ctladdr=<test at server.domain.com> (26/0), delay=00:00:00,
xdelay=00:00:00, mailer=prog, pri=30760, dsn=5.3.0, stat=unknown mailer
error 2

server1 sm-mta[624]: k0LDB3ZM000623: k0LDB3ZM000624: DSN: unknown mailer
error 2