I'm using Zimbra. How do I set up a distribution list with aliases?

You can accomplish this by using the zmprov (Provisioning) tool.

The zmprov tool performs all provisioning tasks in Zimbra LDAP, including creating accounts, aliases, domains, distribution lists, and calendar resources. Each operation is invoked through command-line options, each of which has a long name and a short name.

To create a distribution list, for example, you would invoke the following command:

zmprov cdl example-list@domain.com

To add aliases to that list, you would invoke the following command:

zmprov adla example-list@domain|id alias@domain2.com