Thunderbird, tools, junk mail controls.
Check, configure junk settings for (I use my email address vs local folders)
Check, do not mark messages as junk if sender is in my personal address book
Check, Move incoming messages determined to be junk to
"junk" folder on local folders
Check, Automaticly delete junk messages older than (I use 30 days)
Work your way through them all, figure out what you like, what you want to do, etc.
Its really not hard.
it works just as good as mailwasher, without having to run a second program.