MailStore - MailStore Home - A 100% free single-private-user desktop solution
Mailwasher - Over 8 million people use MailWasher as their spam filter
Gmvault - Backup the emails in your Gmail account.
SPAMfighter - SPAMfighter and Microsoft have built the strongest and most effective anti spam filter for Outlook, Windows Live Mail, Outlook Express & Thunderbird
Mail Backup X - Your one stop mail backup and archiving tool for Mac.
Spam Reader - Spam Reader is a free anti-spam add-on for Microsoft Outlook.