Search Sent folder for "To:" addresses, not "From:"
When I'm searching sent mail, I NEVER need to search on the From: message, and am ALWAYS looking for a message I sent to someone. I'm sure there are exceptions to that for some people and accounts, but in general, that would be the intelligent field to be searching for when in the Sent folder.
Completely agree. The likelihood of searching SENT mail that is FROM a specific person is slim to none. Default should be TO.