In reply to:

Pegasus Mail and the others have something similar.


The outstanding Pegasus (sourced in your turangawaewae, CapK) does have very good filtering options. I don't use them, as I use its selective download feature instead. I check the headers of my email before downloading them from the server, and delete spam straight off my ISP's server, so that it never even clutters up my own trashbox.