[X4U] Smart recipient lists?

[net kat]

I'm really starting to dig Smart this and Smart that...and wondered  
if there's a way to create Smart recipient lists in Mail.app?

Examples:

An e-mail that would go to anyone who is family.
An e-mail that would go to anyone who is a client.
An e-mail that would go to any client who has responded..

etc.

Guess the criteria could be controlled in Address book? Maybe Address  
Book would be the app to have this Smartness applied to it?

Family members don't increase/decrease that rapidly, but clients do,  
or other types of lists do.

would be cool if such a Smart Recipient list would not include all  
other recipients  in the To field, esp. for clients, who would see  
only their own name in the To field.

netkat