As others have mentioned, there is a CONTENT_FILTER template available
(depending on how recent the version is of your site software).  How it
is used is open to some personal interpretation.  Here's one I have in
place:

Subject: Out of office
Action: MODERATE OOO messages are not allowed on this list.
Subject: out of office
Action: MODERATE OOO messages are not allowed on this list.
Subject: Out of the office
Action: MODERATE OOO messages are not allowed on this list.
Text: Out of office
Action: MODERATE OOO messages are not allowed on this list.
Text: Out of the office
Action: MODERATE OOO messages are not allowed on this list.
Text: out of the office
Action: MODERATE OOO messages are not allowed on this list.
Text: OutoftheOffice
Action: MODERATE OOO messages are not allowed on this list.
Subject: OutoftheOffice
Action: MODERATE OOO messages are not allowed on this list.
Text: out of my office
Action: MODERATE OOO messages are not allowed on this list.
Text: away from my office
Action: MODERATE OOO messages are not allowed on this list.
Subject::
Action: REJECT Please resubmit your message with a non-blank subject.

Note that in the case of the "MODERATE" action choice, the following
text "OOO messages are not allowed on this list." is merely documentary
within the template, LISTSERV does nothing with it.  I have had one case
where someone wrote within the body of their message one of the phrases
above (in context of advising the list of some vacation plans coming
up), and wanted to know why their mail to the list was coming back to
them for approval (it was the list owner) instead of just going out -
and forwarded to me the approval request.  I recognized the trigger
phrase and explained to them what was going on.  This illustrates my
logic for using Moderate instead of Reject here, but that depends on the
list involved, and how much bother the owner/moderator is willing to
tolerate with actual vacation rule messages coming in.  I'm also
concerned that rejecting auto-reply messages might trigger a mail loop,
if the other side auto-replies to the rejection notice.



>>> [log in to unmask] 4/12/2007 3:30:10 PM >>>
I have a request from a list owner to block vacation reply messages to
the list.  I told her that I have no control over auto-reply systems in
other places, but I might be able to do something about our own. Can I?

What I'm thinking would work would be to set up a regular expression
filter, probably on the subject line but if an arbitrary header line
could be used that would be better. Alternately, is there a specific
header line that Listserv uses to recognize auto-replies that we could
insert into our system?

Any help appreciated.

Thanks,

 - Mark
-- 

Mark Berman, Director for Networks & Systems 
Williams College, OIT, Jesup Hall 
Williamstown, MA. 01267             413-597-2092