More SPIM (spam on IM)

["W. Martin Borgert" <debacle@debian.org>]

Hi,

unfortunately, we see more SPIM in our Debian XMPP accounts:

 - invitation SPIM: this is a completely new phenomenon to me,
   but it was long expected, as soon as people block non-contacts

 - SPIM passing the default Gajim anti-spam question
   ("Please answer: 12 x 12?"). I changed the question slightly
   and that helped, so their math parser is really bad :~)
   Please be inventive with your questions!

I got nice filter rules for prosody now from two experienced
XMPP admins, that we can block at least 80% of SPIM really soon
now. (Still waiting for access to our server, though.)

Cheers