[Mailman-Users] postfix with mailman : can't reply mail to mailman?

[doug]

hello:)
I've success build postfix and mailman.
  Postfix seems working good.
 I subscript a mail address to mailman.
Soon , I got the confirm mail from mailman.
And I reply the mail , but the "welcome mail " never back to
the mail address???
I have not get  ""Undelivered Mail Returned to Sender"" .
So maybe the problem is in mailman wrappper??
I've read INSTALL in mailman and reconfigure mailman --with-mail-gid=nobody.