[Mimedefang] Tagging defanged messages for procmail filter

[Kenneth Porter]

I use procmail to filter all my mail. I'd like to move all messages that have
had dangerous attachments removed filtered to a specific folder. I could use a
body filter for "WARNING: This e-mail has been altered by MIMEDefang" but it
seems like adding a header to test for would be more efficient. Is anyone
doing this? What header do you use?