[Mimedefang] SWEN filter

[Kenneth Porter]

Just need a bit of Perl help. I have this in my .procmailrc:

# case-sensitive header search, SWEN uses FROM, TO, SUBJECT
# note that the ^TO macro has to be escaped to match the literal word TO.

:0 D
* ^FROM:
* \^TO:
* ^SUBJECT:
|/usr/local/bin/dmail +mail/IT/SWEN

I've seen no false positives after several months of operation, so I'd like 
to move this into MD to reject any matches. What would be the equivalent 
Perl expression?