Clyton

Clyton is an email client for Windows that focuses on security and spam filtering. The spam filter is highly configurable and supports DNS blacklist checking (DNSBL).

Expect 85% of spam to be eliminated with the default configuration. Email that is suspicious but not obviously spam is quarantined for 24 hours and then retested, providing the blacklist enough time to react to new spam sources. Received email cannot run scripts, download multimedia, or use embedded objects without your approval. The built-in address book supports personalized mass-mailings. Other features include encrypted storage, whitelisting, a powerful HTML editor, attachment viewing, message drag and drop, custom message templates, USB flash drive installation, OAuth, and much more.