I want to group first by flag status and then by Received date, but
have the same collapsable headers available in the Received that you
get if you group first by Received date.

It looks like it may not be possible, but thought I would post to see.
Thanks! Following is the example.

So:

Group: Flag Color Unflagged
(Then emails by date with this flag color grouped as the following)
Date: Today
Date: Yesterday
Etc.

Instead of

Group: Flag Color Unflagged
(Where the groups by date are specific including the time).
Date: 6/9/2006 4:18 PM
Date: 6/9/2006 4:12 PM
Date: 6/9/2006 12:36 PM
Date: 6/8/2006 5:36 PM
Etc.