I am unaware of anyway to re-send a message back to a user. However, I would tag the message, such as the subject and allow the message to pass to the end user, and let them decide if it is spam or not. Yyou can use MF to Copy the message to a special mail box where you can check the messages, but this is a labor intensive task, and trust me, from experience, you don't want to do it.

Example:
[TCC SPAM FILTER: SPAM PROBABILITY 89 %]Auctiva Checkout - Item: 200483619438 (verification)

The rule above appended the subject of the email with an alert telling that user that the message has a spam probability of 89%. Now in the above example, this was a legit message. So you have to be careful, what may be spam to you may be legit mail for someone else.