The mailing list for listmasters using Sympa

["John Levine" <address@concealed>]

I have a moderated list (the venerable Telecom Digest) where the
moderation all happens somewhere else, and the moderator sends the
approved messages to the list which posts them.  When I was using mj2
he added an Approved: header with a password which was stripped off as
they were posted.  The From: lines are unpredictable and most are not
subscribers to the list.

What's an easy way to get the same effect in Sympa?  The messages pass
through a script of mine here on the way in so I can munge them
however I need to, although I would prefer not to munge them very
much.

R's,
John