A distribution list is a feature of zimbra.
You can set them up in the Administration Console.
A distribution list is an e-mail address list at your domain. Let’s say your domain is domain.com, and you want to create a list that has all of your web developers. We’ll call it
dev@domain.com
You can add their accounts to the distribution list, and all e-mails that go to that account (
dev@domain.com) get sent to the recipients on the distribution list (all of the developers on the list).