[Mimedefang] Rejecting Cyrillic

[Kenneth Porter]

I've noticed a lot of spam lately in codepage Windows-1251 (Cyrillic). I'd 
like to reject it with a "Cyrillic not understood; please resubmit as 
Unicode". Is there a canonical MIMEDefang idiom for doing that?

I'm seeing the codepage referenced both in the subject line and in the MIME 
part's Content-type header.

I could, of course, write a SpamAssassin rule for this, but it seems that 
since none of my users have any use for Cyrillic, I could bounce it before 
SA needed to look at it, and with a message that would be meaningful to a 
legitimate sender.