[Mailman-Users] Mailman list sends but doesn't receive mail.

[JRC Groups]

Hello, All.

I've just set up my first Mailman mailing list in OS X Server. It sends mail
as welcome notifications were received by several different members
subscribed to the mailing list. However, it doesn't seem to be receiving
e-mail. All attempts I've made have resulted in Delivery Failure
Notifications.

This is the text returned with this Delivery Failure Notifications:

> Delivery to the following recipient failed permanently:
>
>      list at 3domain.com
>
> Technical details of permanent failure:
> Google tried to deliver your message, but it was rejected by the recipient
> domain. We recommend contacting the other email provider for further
> information about the cause of this error. The error that the other server
> returned was: 550 550 5.1.1 <list at domain.com>: Recipient address rejected:
> User unknown in virtual alias table (state 14).

What could be the cause ?

In order for a Mailman list to work properly do I need to create an account
for it in Workgroup Manager with its e-mail address ?

Sorry if this is a simple question but I am not an IT specialist and don't
have any experience with Mailman.

Thank you in advance,

Joe