First thing - stop using the 'bounce'! It is not as efficient as Mailwasher think. Some clever people out there can tell that it's a bounce from the user rather than the server by how long it takes! QED, you exist, so we'll send more spam.
Spam is a sad fact of life, But I have noticed a general, if gentle, decrease in the time I've been using Mailwasher - but without bouncing.
Treat it like junk mail through the letter box and dump it as soon as it arrives.
HTH a bit