Thanks for your reply alexkelly.
So, I've got to use zmmailbox from command line to do what I'm needing. Right??? Or there is a way to do it through the web administration interface?
Note: Same as your case, we don't have and need login for the common accounts, logins are one per human being.
This wiki I've found, it might help me?
Zmmailbox - Zimbra :: Wiki
Santiago