KMail

Boost your email and skyrocket your productivity with the best email client for Windows and macOS. eM Client is a fully-featured email client with a clean and easy-to-use interface. It also offers features for calendars, tasks, contacts, notes, and chat. eM Client's compatibility is unmatched. You can connect to any email service – it will work. This email client works seamlessly with Google Workspace, Office 365, Outlook, Exchange and virtually all conceivable email technologies. Integrates with Online meeting tools such as Zoom, MS Teams, Google Meet and more. eM Client enhances email communication for professionals and home users alike. It is the only email app on the market with the full support of server-side rules and search, instant message translation, "Snooze email" and “Watch for reply” features + easy to use email encryption (PGP and S/MIME). It also works perfectly with Gmail, including support for tags and signature synchronization.

Clyton is an email client with advanced security and spam filtering features. 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. The built-in address book supports personalized mass-mailings. Received email cannot run scripts, download multimedia, or use embedded objects without your approval. Other features include encrypted storage, whitelisting, powerful HTML editor, attachment viewer, message drag and drop, custom message templates, SSL encryption, USB flash drive installation, and much more.