Lion Mail has a new feature that lets you sort your mail. This is a big help if you are searching for, say a message that sent to a specific person.
With Mail open decide what you want to sort (all your mail, your sent mail, your trash, your junk). Highlight that choice. Then select View > Sort By. Then from the options presented make your selections. Perhaps “To” in the first set and “Descending” in the second.
In this example every email you have sent to Joe Sample will be clumped together. You still have to scroll through the list to find Joe’s group, but what a time saver this is.
The only modifier on this will be whatever time limit you have set on how long you keep messages. If you want to check your settings, open Mail Preferences > Accounts > Mailbox Behaviors and you can make changes if you wish.