MailMate App allows for very fibre grained search. But it isn’t obvious how to set the default search.
Use ⌥ + ⌘ F will open the search bar at the top of the window. Click on the search field will pop up the following menu where you see a lot of options. I’ve been using search in the unquoted body text (the email from the other person but not my responses) but I want to change back to searching on the “from”
So I select the From selection that I want to use:
Then used the Menu, Edit, Find, Use as Default Search:
and now that search will be the default.