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 many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Horde are mailcow: dockerized, Mailpile, Rainloop and SOGo.
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...).
Web-based team collaboration suite combining email client, calendar, contact and task tools, CRM, project and file management, file sharing, trouble tickets, Rocket.Chat chat, and Collabora online editing. Offers open source, self-hosted, and SaaS options.
OBM is a free messaging and collaboration platform useful for just a couple to many thousands of users with strong support for mobile devices.
Postaci (Turkish for Postman) is multiplatform Webmail software which is database independent, multilanguage, POP3/IMAP, and fully MIME-compatible. While using POP3 mode to fetch messages it uses database fields to simulate IMAP folders, on which you can save, move, delete, and...
Unofficial, free and open-source Google Inbox Desktop App. Built using electron, Inboxer includes a menu bar which is globalmenu compatible and works, and keyboard shortcuts.
NeoMail is a web-based mail client that allows users to access their mail spools and send messages. It does not require a POP3 server, or any shell access for the users. It interfaces directly with user mail spools.
Afterlogic Aurora is an enterprise collaboration system for small and medium-sized business. Aurora provides collaboration of webmail, contacts, calendar, files and helpdesk modules.
Spain
EU
Germany
United States