rblsmtpd and not bouncing

[Michael T. Babcock]

I would like to offer an option similar to pobox.com's [spam: 84%]
"Subject:" munging for incoming messages from RBL or RSS listed sites.
Instead of actually bouncing the message as RBLSMTPD does, allow the
message but add [spam - rbl] or [spam - rss] or the like to the Subject:
field of the messages in question.

I'm wondering if anyone else has done this before I go making a
completely modified version of rblsmtpd to do so.