Alternatives to Citadel for all platforms with any license

Platforms

Desktop

Web / Online

Indie / Classic

  • Zimbra Collaboration Suite icon

    Zimbra Collaboration Suite

    Zimbra Collaboration is an open, secure collaboration tool for email, calendaring, tasks and more. With the most innovative web application available today, Zimbra boosts the productivity of users on any desktop and dramatically...

    Freemium Linux Web / Cloud

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  • OX Open-Xchange icon

    OX Open-Xchange

    Open-Xchange Server 6 is the most advanced Linux based Groupware solution f. Open-Xchange Server 6 is superior in the following areas: • Open-Xchange Server 6 offers most comprehensive Groupware functionality based on modern user...

    Open Source Linux Web / Cloud

  • Microsoft Exchange Server icon

    Microsoft Exchange Server

    Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft. It is part of the Microsoft Servers line of server products and is widely used by enterprises using Microsoft infrastructure...

    Commercial Windows Web / Cloud

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  • Zarafa icon

    Zarafa

    Open Source Collaboration, providing integration with your existing Linux mailserver, native mobile phone support, Outlook "Look & Feel" webaccess and stable Outlook sharing (100% MAPI).

    Commercial Mac Windows Linux Web / Cloud

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  • hMail Server icon

    hMail Server

    hMailServer is a free e-mail server for Microsoft Windows. Its used by Internet service providers, companies, governments, schools and enthusiasts in all parts of the world. It supports the common e-mail protocols (IMAP, SMTP and...

    Open Source Windows

  • MDaemon Messaging Server icon

    MDaemon Messaging Server

    MDaemon Messaging Server software for Windows can be deployed in virtual, hosted cloud or private on-premise environments. It is used by businesses in over 90 countries and over 25 languages worldwide. MDaemon includes client and...

    Commercial Windows

  • eGroupWare icon

    eGroupWare

    Egroupware is a web based software for team collaboration, central data management and CRM: email client, online calendar, contact and task management, project and file management, trouble ticket system, synchronization.

    Open Source Linux Web / Cloud

  • Atmail Email Server icon

    Atmail Email Server

    Atmail webmail system offers a webmail client, email server platform and mailserver appliance for Linux, Unix and Windows. Features: Webmail Calendar Addressbook IMAP, POP or Exchange WebSync SMTP/POP3/IMAP server Explore the...

    Commercial Linux Web / Cloud

  • Xeams icon

    Xeams

    Xeams is a secure & powerful mail server for Windows, Linux, Solaris, MacOSX and other flavors or UNIX, which supports SMTP, POP3, and IMAP. It includes a powerful spam/junk filtering engine that elimates up to 99% of junk email...

    Free Personal Mac Windows Linux BSD

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  • SmarterMail Mail Server icon

    SmarterMail Mail Server

    SmarterMail delivers Exchange-level email server software features for a fraction of the cost. With lower hardware requirements, superior stability and reduced maintenance costs, SmarterMail has significantly lower Total Cost of...

    Freemium Windows

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  • iMail icon

    iMail

    Fast, safe, heavy mail solution. Web-client access, LAN or WAN self-hosted server, maintenance-free design. No Windows server and database server required, unlimited mail accounts, storage, attachment size, custom logo. Free for...

    Free Windows Self-Hosted

    No features added Add a feature

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