[Mailman-Users] Stripping sig files

Stephen J. Turnbull stephen at xemacs.org
Sat Dec 18 09:09:57 CET 2010

bruce clark writes:

 > My problem: the users on my lists are waging a low-level war with  
 > their sig files. I do not allow commercial posting so they have  
 > started creating sig files with their commercial messages inside them.

First, consider whether this is really so bad.  I know I would be
annoyed if I were in your position -- these folks are deliberately
flouting your rules -- but do the other users really care?  If it's in
the sig, maybe nobody is looking at it unless they want to.  (No need
to explain to us; I just want to point out that the list owner is very
likely to be exceptionally sensitive to this kind of behavior, and
maybe it's not causing problems for the general members any more.)

If you think that something should be done, I second Mark's suggestion
of moderating "offenders" (filtering out whole posts as needed).  If I
understand the situation correctly, these really are *your* lists.
You may or may not be paying for the service in money, but you sure
have invested your time and effort and stress.  In Internet tradition,
you have every right to behave as capriciously as you like in allowing
traffic on your lists; simply enforcing the rules that have been
announced gives nobody *any* ground for complaint.  (That's not going
to stop the prima donnas from screeching, and that may be a real
problem for you, but for stress reduction, it's important that you
realize that they are in the wrong, you are in the right, and that is
that.  Then you can do what needs doing "in sorrow rather than in

[[[ aside:
 > listed the mime types of images to be filtered,

Hey, don't run yourself down as "not an admin"!  There are plenty of
people who never figure that one out!

 > but there is still text in the sig files that I would like to
 > delete before the mail reaches the list.

This is not a great idea IMO.  Without agreement from the authors, it
is legally (copyright), ethically (IMHO, YMMV), and technically
problematic.  The first two are up to your judgment.  The technical
issue is that, unlike images and other multimedia attachments, the
signature is just text that is automatically inserted at the end of
the message, often without the author ever seeing it.  Conventionally
a signature is preceded by a line that contains the characters "-- "
(HYPHEN HYPHEN SPACE), no more, no less.  This allows readers with
capable mail programs to suppress display of the signature.

I infer from your post that the offenders are doing so deliberately.
If so, they can add it to their messages in an unconventional way that
an automatic sig-stripper won't recognize.  You can update the
stripper for new separators, but that's no fun for you.  It's also
beyond current technology to recognize commercial content and strip
only that.  So you are going to have to do the work of checking for
forbidden content.  If you want it removed, you'll probably have to
hand edit each offending message.

 > should I be putting my energy somewhere else? I guess I would somehow  
 > need to intercept the mail between the sender and the receiver and  
 > somehow 'fix' it?

I recommend, don't fix it, reject it.  Specifically, in the mailman
web interface, go to the membership pages, then to the problematic
user, and switch on the moderated checkbox for that member.

When their mail arrives, you (the list owner, and any assistant
moderators you appoint) will be told by Mailman.  If it has any
commercial content, reject it (there are four choices, "hold, approve,
reject, discard"; reject sends a message back to the author explaining
why, discard drops it in a black hole).  Have a canned message like
"Commercial content is forbidden on this list.  For technical reasons
it cannot be automatically removed.  Please resend your post without
such content."  Let people think it's being done by a robot; that
often keeps them from yelling too much.

If the mail is legitimate, let it through.

You needn't do this operation very often; Mailman will hold on to the
messages forever.  Remember, they are disobeying the rules, and
deliberately if I understand correctly.  You have no obligation to do
anything for them; reviewing the moderation queue every few days at
your convenience is *more* than they have any right to ask.  You do
this *for yourself*, because you want to see the on-topic content they
send, or because you want to support your other members who do.

When a person sends a couple of posts without objectionable content,
or if they send a sincere apology, turn off moderation for them as
described above.  How quickly to do this is a matter for your
judgment, obviously, but in my experience for most people having to
sit out one heated discussion because their posts don't show up until
after it's over is more than enough to convince them that crossing the
moderator is a bad idea.

 > (and don't suggest that I go around to the offenders' houses and beat  
 > them up - because I've thought of that already)

Well, that might require lawyers and icky stuff like that in the end.
Letting them sit in a corner for a day or five waiting for their oh-
so-important posts to arrive at the list seems like a more appropriate
measure.  What do you think?

Good luck!

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