[Mailman-Users] Question about the "Group mismatch error" when updating mailman service

[Sean]

Dear all

I have a strange question for creating a new list after updating mailman
server.

Currently, I had updated my mailman server to a new machine.
(mailman-2.1.5_2 -> mailman-2.1.9_5)
My server is FreeBSD 7.0, Postfix + mailman 2.1.9_5

And I translate the lists and archives on old machine to new machine.
I called these lists "old lists". The old lists can work correctly on the
new machine.

Now I create a new list by bin/newlist, but it got a error when I send mail
to this new list which is
" "/usr/local/mailman/mail/mailman post eos". Command output: Group mismatch
   error.  Mailman expected the mail wrapper script to be executed as group
   "nobody", but the system's mail server executed the mail script as group
   "mailman".  Try tweaking the mail server to run the script as group
   "nobody", or re-run configure,  providing the command line option
   `--with-mail-gid=mailman'."

So I reinstall mailman server with --with-mail-gid=mailman setting.
Then the new list can work correctly.

But the other question happened. "Group mismatch error" happeded on the old
lists which is
" "/usr/local/mailman/mail/mailman post xip". 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' "

Now I'm confused at this situation because I didn't change the system's mail
server. But it shows that the system's mail server executed the mail script
as group "mailman" and "nobody" after I reinstalled. Why?
How can I solve this question? Can anyone give me any idea?

Thanks a lot!!!

Best Regards,
Sean