I haven't used rewrite before, but perhaps using "junk" might achieve what you're looking for.
filter "rdns" phase connect match !rdns junk filter "fcrdns" phase connect match !fcrdns junk action "local_mail" maildir junk alias <aliases> 'X-Spam: yes' header is added and messages with that header will end up in the junk folder. Personally, I just disconnect on no rdns, and my logs reaffirm my decision. Other SMTP servers aren't accepting those messages, so why should I receive them? -- Ethan
