Set Agent to run when mail moved to a specific folder?

I need to write an agent that triggers whenever mail is put into a specific folder. The pseudo code is:

  1. Manual process: users puts mail into a specific folder

  2. Automatic process: a copy of the e-mail is sent to another e-mail address.

If this can’t be done, the user is OK with an agent that runs against the folder every half hour, but how would I tell which items in the folder had already been processed and which hadn’t without modifying the mail template to add a flag field?

Thanks

Subject: Use the queryaddtofolder event