Blocking Emails using Cyrillic Characters

The problem

We have dozens of email users, none of whom ever comminicate with anyone using Cyrillic characters but who get a LOT of email (spam) in Cyrillic languages lately. Hundreds of these emails are passing through Spamassassin daily, causing some of my users to ask why our spam filtering does not mark those emails.

Using procmail would seem to be the simplest way to filter out this mail. A simple recipe that should work well (actually 2) is:

:0:
* Subject:.*koi8-r
/var/www/web1/user/web1_joe/Maildir/crap/

:0:
* Subject:.*windows-1251
/var/www/web1/user/web1_joe/Maildir/crap/

These assume that the character set is in the subject line, which seems almost always to be true.

Is there some way I can add these recipes universally so that they would work on ALL incoming email for all users? Seems like at one time we used a .procmailrc file in the /etc/ directory that was universal....?

Are there any other ways anyone knows of to deal with the flood of Cyrillic spam (assumed since it is NOT readable to anyone I know!)? Some of my users complain of getting 30 or 40 of these mails a day.

Thanks,

Richard