Guess what: I had to resent it to the list. My .signature was added, and thus the mail had some lines starting with a letter, and the recipe did not fire anymore.

Aha, my problem turned out to be similar. I was dealing with Russian in cyrillics, and I had to change all occurrences of "a-z" in rc.request by adding the range for cyrillics. Otherwise they were treated as non-letters.

Thanks for all responses I received, they were very helpful.

- M