Best Thunderbird Alternatives in 2021

    Thunderbird is described as 'free, open source, cross-platform e-mail, news and instant messaging client. The project strategy is modeled after Mozilla Firefox' and is one of the leading apps in the News & Books category. There are more than 50 alternatives to Thunderbird for a variety of platforms, including Windows, Mac, Linux, Android and iPhone. The best alternative is K-9 Mail, which is both free and Open Source. Other great apps like Thunderbird are eM Client (Freemium), Evolution (Free, Open Source), Feedly (Freemium) and Claws Mail (Free, Open Source).

    This page was last updated Jun 24, 2021

    1. Pegasus Mail is a free, standards-based electronic mail client suitable for use by single or multiple users on single computers or on local area networks.
      show more
    2. Collaborative email and threaded group chat for productive teams. A single app for all your internal and external communication. As foreign as chat is to email, mixing them unleashes unforeseen possibilities. Missive is the one app you’ll ever need to manage your work life.
      show more

      • Free PersonalProprietary
      • Mac
      • Windows
      • Linux
      The free Zimbra Desktop client allows you to meld the online and offline worlds – storing and synching your email, calendar, contacts, files and documents in the cloud, yet having them locally accessible when on the road.


      From download page: "The Zimbra Desktop is no longer supported. It will reach the end of Technical Guidance October 1, 2019.".


      show more
      Zimbra Desktop vs Thunderbird opinions
      Some users think Zimbra Desktop is a great alternative to Thunderbird, some don't.
      michael111 tried it over a few weeks, all you need for office users
      Positive comment over 2 years ago

      This one goes beyond the features and qualities of Thunderbird which is the very reason I am looking for an alternative!
      Positive comment over 4 years ago

      • FreeOpen Source
      • Online
      • Self-Hosted
      A mail app for Nextcloud - Integration with other Nextcloud apps! Currently Contacts, Calendar & Files – more to come.
      No screenshots yet
      • Mac
      • S/MIME
      • OpenPGP
      MailMate is an IMAP e-mail client for Mac featuring extensive keyboard control, Markdown supported email composition, advanced search conditions and drill-down search links, equally advanced smart mailboxes, automatic signature handling, cryptographic encryption/signing...
      show more

    3. aerc is an email client that runs in your terminal. It's highly efficient and extensible, perfect for the discerning hacker.
      show more
    4. Mulberry is a powerful, easy to use electronic mail (email) and calendar program that allows you to send, access, and manage email and calendars. Mulberry also helps you manage other related information, such as contact information.


      The project is no longer developed. Last version, 4.0.8, released in February 2007, can be still downloaded from the official website.

    5. Single collaborative customer support dashboard for all of your projects. Chat with your customers and your team members using single workspace. If it's an email sent to or a chat request from, it all goes into the same Plumm inbox.
      show more
    6. mu is a tool for dealing with e-mail messages stored in the Maildir-format, on Unix-like systems.
      show more
      • FreeProprietary
      • Online
      Check your email on the web using our Webmail Application. With you can check your email from anywhere using our Webmail service. No registration required and we never share your information with anyone. Just enter your email address and password!
    Showing 50 of 89 alternatives