Loved MailWasher, used it for many years. Had one rule I wrote to nail spam that spoofed my own email addresses, the rule checked the computer name of the sending PC.

Two things caused me to discontinue using MailWasher.
1) The missus hated, loathed, the fact that MailWasher was a separate process from checking the email. She likes the integrated solutions from other providers, such as Norton and ZoneLabs.

2) Every four months or so, MailWasher would crash and take out my preferences files, requiring me to use a backup. This destruction of data made me nervous about the product. Tech support was no help (they said, use your backups).