Cyrus IMAP
Cyrus IMAP is an email, contacts and calendar server. Cyrus is free and open source.
Features:
Speed
Security
Efficiency
Search
CardDAV and CalDAV support
Robust data storage
Replication
Scalable for large installations
Flexible filtering support through Sieve
Supports antivirus and antispam toolkits
Handles deliverability: SPF, DKIM, DMARC
Extensive authentication options, through Cyrus SASL
JMAP support
Long list of supported standards
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SmarterMail
SmarterMail is the ideal Microsoft Exchange alternative. First, it's the only business email server on the market that offers native support for the protocols that power Exchange: MAPI, EWS, and EAS. It does this without the need for any additional software or plug-ins for Microsoft Outlook or other clients -- desktop and mobile! Best of all, it offers all of the features of Exchange, but at a FRACTION of the cost. In addition, features like audio and video group chat, and Online Meetings for team meetings and group collaboration are included at no extra charge. SmarterMail is the perfect solution for businesses of all sizes, and in any industry that want Exchange-level functionality, but without the high costs associated with Exchange. It's designed to provide the functionality businesses need, without sacrificing secure, reliable access to business, and personal, communication.
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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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Kopano
We provide you with your digitally sovereign solution to keep track of your e-mails and calendars, to organize yourself with tasks or to stay in contact with team colleagues via video meeting. Kopano Groupware is an e-mail and calendaring solution, which can be operated digitally sovereign. Its functionality is comparable to that of Microsoft Outlook and Exchange. Kopano Groupware installations can be operated with more than 100,000 users. Kopano Groupware is an e-mail and calendar server that provides users with their daily communication and organizational data on all devices and connects teams. Data can be jointly edited in public folders or shared with others from your own inbox.
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