Clyton
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.
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eM Client
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.
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Proton Mail
Proton Mail is the simplest way to protect your communications with built-in end-to-end encryption. Prevent data breaches, stay compliant with regulations like GDPR and HIPAA, and earn client trust. Protected by Swiss privacy laws and trusted by over 50,000 businesses, Proton Mail keeps your business data confidential and under your control. With Proton Mail and Calendar, your team can securely manage their inbox and schedule, while your organization maintains a professional presence with support for custom email domains and personalized branding. And with the Easy Switch tool, migrating from Google or Microsoft is seamless, no IT expertise required.
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Hermes SEG
Hermes SEG is a free, open-source secure email gateway and server. It delivers spam, virus, and malware protection using SpamAssassin, ClamAV, and Amavisd-new, along with full encryption in transit and at rest via SMTP TLS, S/MIME, PGP, encrypted PDF (CipherMail), and Dovecot mail-crypt. It includes email archiving and integrated mailbox hosting with quotas, aliases, shared folders, Sieve rules, vacation replies, and mobile auto-configuration. Collaboration features come through Nextcloud (webmail, file sync, calendars, contacts). Identity and access are managed with OpenLDAP and Authelia, supporting SSO and MFA (TOTP, WebAuthn, Duo). It also enforces modern authentication standards: SPF, DKIM, DMARC, and ARC.
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