Snow Leopard Server 10.6.6 Mailman settigns

 Thanks in advance to everyone that will post to help me with this issue.

I config mail on the Snow Leopard Server, created my A record and MX record, created the correct DNS settings and had my ISP create a PRT record to point back to my static IP. All works correctly. If I send mail to jc@netwebglobal.biz or pam@netwebglobal.biz i can get the e-mail via a client or on the web interface. here is the problem that I'm having with mailman.

When I created the mailman account it asked for a password and a administrative e-mail address, which I set to student@netwebglobal.biz. ( see attached file) then i added the users.
the users are set to subscribe automatically and indeed they are. As soon as I add the user and check on the web to make sure i see the e-mail that the mailman software sends automatically. the problem is when I send another e-mail, the use dose not get it, unless ( see attached file ) the user under workgroup manager has student as an alias. ( see attached file ).
what can I do to correct this problem as when I tried to add student as an alias on another user it as the the name is already in use, which is understandable.

Thanks!
user-pam.png
user-jc.png
mailman-admin-e-mail.png