I have a list of user whom i want to allow sending the mail to a specific distribution list. For example i have a distribution list say "email@example.com". Now i want to allow only "firstname.lastname@example.org" to send mail to this distribution list. So, how can I do this in Zimbra? How i can do the sender restrictions on distribution list in zimbra? I am able to do this in Exchange 2007 but didn't get any option in Zimbra.