[Mailman-Users] User with same name of a mailman list not receiving e-mails

[Centro de Apoio Técnico da APM]

The problem is this:

I have a user with mail account and a mailing-list running in Mailman  
with the same name of the user.

The email for example is this <user at domain.com> and the e-mail of the  
list is this <user at mailinglistsubdomain.com>.

When I send a message to the <user at domain.com>, the message is  
relayed to the list (but not posted) and not to the local box. If I  
send a message to the list there is no problem.

How can I resolve this?
I mean, I want the user to receive the message. Pure and simple.

Xserve   Mac OS X (10.3.9)

João Loureiro.