Mail rule for group journaling

We want to enable the mail journaling feature to capture all mail for a select group of users, our investment department. Mail rules have considerable flexibility but I am not able to see how to limit the selection to only include the members of this group. While I could put each member into the rule individually, it would not be efficient with 400+ members (that seem to have frequent changes). We plan to look at each addressing field (To, From, CC, BCC) for this membership inclusion to conform with federal regulations.

Subject: Mail rule for group journaling

I want to do this same thing. How did you go about it?