On my LISTSERV list, how can I restrict who is allowed to post messages?

To restrict who can post to your LISTSERV list, specify that the list be moderated. All mail will then require the moderator's approval before being posted to the list.

As list owner, you select the moderators and editors for your list; moderators can approve postings, while editors may post to the list without moderator approval.

For detailed instructions on configuring a moderated list, see In LISTSERV, how do I set up a moderated list?