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    Open Source Horde Alternatives

    The best open source alternative to Horde is Roundcube. If that doesn't suit you, our users have ranked more than 25 alternatives to Horde and 19 is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Horde are Rainloop (Free, Open Source), Mailpile (Free, Open Source), mailcow: dockerized (Free, Open Source) and Zimbra Collaboration Suite (Freemium, Open Source).

    This page was last updated Apr 22, 2021

    1. Roundcube webmail is a browser-based multilingual IMAP client with an application-like user interface. It provides full functionality you expect from an e-mail client, including MIME support, address book, folder manipulation, message searching and spell checking.
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      • FreeOpen Source
      • Online
      • Self-Hosted
      • Nextcloud
      • JavaScript
      • PHP
      • Cloudron
      Simple, modern & fast web-based email client. Modest system requirements, decent performance, simple installation and upgrade, no database required. All these make RainLoop Webmail a perfect choice for your email solution.
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    2. Mailpile is a modern, fast web-mail client with user-friendly encryption and privacy features. The development of Mailpile is funded by a large community of backers and all code related to the project is and will be released under an OSI approved Free Software license.


      1.0.0 Release Candidate 6 from 2019 is the last version on GitHub ( Possibly the development has been stopped.

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    3. mailcow is a mail server suite based on Dovecot, Postfix, SOGo, Rspamd and other open source software, that provides a modern Web UI for administration.
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    4. 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 reduces TCO compared to legacy platform vendors.
      Zimbra Collaboration Suite vs Horde opinions
      pros, cons and recent comments
      sondrak Similar scope of groupware functionality, including calendar, tasks, etc.
      Positive comment almost 3 years ago


    5. SOGo is groupware server with a focus on scalability and open standards.
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      • FreemiumOpen Source
      • Linux
      • BSD
      • Self-Hosted
      A fully fledged, free email server solution, an open source project (GPL v2). Use official binary packages from Linux/BSD distributions, with both i386 and x86_64 support. Easy, fast deployment in LESS THAN 1 MINUTE. View YouTube Video to check how easy it is.
    6. Microservice based webmail client built with ReactJS and Spring. Minimalistic webmail client which currently has the main features of any other mail client (read mail, compose mail, organize mail folders...).
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      Almost everyone thinks Isotope Mail Client is a great alternative to Horde.
    7. Teknik was created to provide users with web services that they can trust. Services range from url shorteners to pastebins and encrypted file uploads. Teknik Mail is a premium feature available after a donation of $5 only
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    8. SquirrelMail is a standards-based webmail package written in PHP. It includes built-in pure PHP support for the IMAP and SMTP protocols, and all pages render in pure HTML 4.0 (with no JavaScript required) for maximum compatibility across browsers.
    Showing 10 of 19 alternatives