To prevent your favorite newsletters from being filtered as spam by MailWasher, you can add their senders as friends. I've whitelisted "about.com" in this way to ensure I'm always getting my About newsletters, for example.
Make Sure MailWasher Doesn't Think Important Mail is Spam
To tell MailWasher what important messages and newsletters are not spam.
- Select Tools | Blacklist & friends list from the menu in MailWasher.
- Click Add... on the right, the Friends list side.
- Make sure Plain email address is selected.
- Type email address you want to whitelist in MailWasher.
- To whitelist a complete domain, precede the domain name with the wildcard character '*' which matches any character ("*domain.com", for example).
- To whitelist all About newsletters type "*about.com".
- Click OK.
- Click OK again.

