Open Source Microsoft Office Outlook Alternatives

    The best open source alternative to Microsoft Office Outlook is Thunderbird, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 100 alternatives to Microsoft Office Outlook and many of them is open source so hopefully you can find a suitable replacement. Other interesting open source alternatives to Microsoft Office Outlook are Evolution (Free, Open Source), K-9 Mail (Free, Open Source), Mailspring (Freemium, Open Source) and Geary (Free, Open Source).

    The list of alternatives was last updated May 24, 2021

    Platforms

    • Windows
    • Mac
    • Linux
    • Online
    • Android
    • iPhone
    • Android Tablet
    • iPad
    • BSD
    • Windows Phone
    • Apple Watch
    • Self-Hosted
    • Windows S
    • OpenPGP
    • S/MIME
    • Kindle Fire
    • Haiku
    • Chrome OS
    • Symbian S60
    • Windows Mobile

    Features

    • Calendar
    • Multiple Account support
    • Support for IMAP
    • POP3 Support
    • Portable
    • Todos
    • Exchange
    • Task Management
    • Unified inbox
    • Multiple languages
    • Organize mails
    • Customizable
    • Calendar integration
    • Night mode/Dark Theme
    • Extensible by Plugins/Extensions
    • Apps that Sync with Google Calendar
    • Gmail integration
    • CalDAV
    • Built-in RSS reader
    • Contacts

    License

    × Clear
    • Free
    • Open Source
    • Paid
    All Filters

    Showing 10 of 33 alternatives