Found via news2notes, this handy
Mail Markup Agent adds an icon to incoming mail to let you see whether you were the main addressee, a cc:, a bcc:, or part of a list from your inbox.
The only deficiency of this agent is that it doesn't work for Internet email unless the sender is sending using RFC822 phrases. It is of course easy to add this, by adding a simple @Contains check for "firstname.lastname" in the SendTo and CopyTo fields, but that also means you should perform an @Replace on the space in the database title to replace it with a "." or "_" (depending on the conversion options you have set in your MTA), and also convert both strings to either uppercase or lowercase.
Of course, if you're exclusively using shortnames then you're screwed. Aah well!
Anyway, point is, it's a nice little agent.