The Best Free Thunderbird AlternativesTop Email Clients & Calendar Apps like Thunderbird

The best free alternative to Thunderbird is K-9 Mail, which is also Open Source. If that doesn't suit you, our users have ranked more than 50 alternatives to Thunderbird and loads of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to Thunderbird are Claws Mail, Evolution, SeaMonkey and Geary.

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Thunderbird alternatives are mainly Email Clients but may also be Calendar Apps or Web Browsers. Filter by these or use the filter bar below if you want a narrower list of alternatives or looking for a specific functionality of Thunderbird.

Thunderbird

2385

Email Client
Free • Open Source

Thunderbird is a free, open source, cross-platform e-mail, news and instant messaging client. The project strategy is modeled after Mozilla Firefox.

More about Thunderbird

Thunderbird alternatives page was last updated Sep 26, 2024

Mailbird

License model

Freemium • Proprietary

Application type

Email Client

Platforms

Windows

K-9 Mail
K-9 is an open source email client for Android with multi-folder sync, email signatures, Bcc-to-self, return-address configuration, keyboard shortcuts, Exchange Support, message flagging, IMAP deletes, saving attachments, configurable notifications and more.
42 K-9 Mail alternatives
License model
- Free • Open Source
Application type
- Email Client
Platforms
- Android
- Android Tablet
- F-Droid
+3
Top K-9 Mail Features
1. Ad-free
2. IMAP Support
3. Multiple Account support
4. Configurable
5. Privacy focused
6. POP3 Support
7. One view multiple accounts
8. PGP Encryption
9. Lightweight
10. Unified inbox
11. No Tracking
12. End-to-End Encryption
Show all NaN K-9 Mail features ▾
K-9 Mail VS Thunderbird
Is K-9 Mail a good alternative to Thunderbird?
Comments about K-9 Mail as an Alternative to Thunderbird

kiminariyamamoto
Keeps the style of working with email as it should be, like we are used to from proper desktop Mail clients. It's unlike modern fancy clients with couple of buttons without even providing an option to view headers.
Top positive comment •Mar 25, 2018
6
sbeiermann
not understanding the negative comments or why most of the positive comments are being heavily downvoted. i came here looking for something that works like thunderbird but for my android phone. i found it, but i guess i'm using the website wrong.
Top positive comment •Apr 24, 2024
0
Guest
wrong platform. K-9 is for android, Thunderbird is not, so K9 is not a valid alternative for Thunderbird users
Top negative comment •Oct 8, 2020
18
Frisk
This is an Android app. NOT an desktop app.
Negative comment •Jul 26, 2023
0
ByteRanger
K-9 Mail is not for desktop operating systems, only Android. So you can't replace Thunderbird unless you are also replacing your desktop with a mobile device.
Negative comment •Jul 25, 2023
0
Show more comments
5 of 20 comments
- Most users think K-9 Mail is a great Thunderbird alternative.
- K-9 Mail is the most popular Android & Android Tablet alternative to Thunderbird.
- K-9 Mail is the most popular Open Source & free alternative to Thunderbird.
- K-9 Mail is Free and Open SourceThunderbird is also Free and Open Source
- K-9 Mail is Privacy focused and LightweightThunderbird is not according to our users

Claws Mail
Claws Mail is an email client (and news reader), based on GTK+, featuring

Quick response Graceful, and sophisticated interface Easy configuration, intuitive operation Abundant features Extensibility Robustness and stability.
80 Claws Mail alternatives
License model
- Free • Open Source
Application types
- Email Client
- Calendar App
Platforms
- Windows
- Linux
- BSD
Top Claws Mail Features
1. Lightweight
2. Extensible by Plugins/Extensions
3. Multiple Account support
4. Spam Filter
5. No registration required
6. Ad-free
7. Privacy focused
8. Works Offline
9. Portable
10. Calendar Integration
11. GPG Encryption
12. Import/Export OPML Feeds
Show all NaN Claws Mail features ▾
Claws Mail VS Thunderbird
Is Claws Mail a good alternative to Thunderbird?
Comments about Claws Mail as an Alternative to Thunderbird

Jonathan DUMONT
Despite the style, Claws is super fast and allow you to programs it with Perl and Python which is great for marketing automation.
Top positive comment •Aug 1, 2019
9
3psilon
It's a good, lightweight alternative, but the UI is clunky and it misses HTML message composing. You have been warned!
Top positive comment •Sep 3, 2017
14
Guest
No HTML compose is the only reason I don't switch to it. We're not in 1980 anymore.
Top negative comment •Sep 28, 2018
16
SViN
I think most people are using gmail accounts or outlook accounts to access their emails. Claws supports Oauth2 to access said accounts but the implementation, is a complete PAIN.

I can only realistically recommend something like this if your email provider is not forcing Oauth2.

I would like for the devs to get to work into making the experience of setting up an account with oauth as painless as thunderbird.
Comment •Sep 20, 2023
1
Guest
very good alternative under linux. I can not say the same under windows since fancy plugin is very buggy.
Positive comment •May 5, 2020
-1
Show more comments
5 of 8 comments
- Most users think Claws Mail is a great Thunderbird alternative.
- Claws Mail is the most popular Windows & Linux alternative to Thunderbird.
- Claws Mail is Free and Open SourceThunderbird is also Free and Open Source
- Claws Mail is Lightweight and Privacy focusedThunderbird is not according to our users

Ad
Mailbird
Mailbird helps individuals and businesses manage emails in one place. This allows you to simplify your workflows. Therefore, spend more time on important tasks.

https://www.getmailbird.com
Learn More
Evolution
Evolution is a personal information management application that provides integrated mail, calendaring, address book and task list functionality.
78 Evolution alternatives
License model
- Free • Open Source
Application types
- Email Client
- Calendar App
Platforms
- Linux
- BSD
- Flathub
- S/MIME
- GNOME
- OpenPGP
+4
Top Evolution Features
1. Calendar Integration
2. Contacts
3. CalDAV Support
4. Calendar View
5. Ad-free
6. Spam Filter
7. Multiple Account support
8. Sync with Google Calendar
9. Extensible by Plugins/Extensions
10. Dark Mode
11. Works Offline
12. GPG Encryption
Show all NaN Evolution features ▾
Evolution VS Thunderbird
Is Evolution a good alternative to Thunderbird?
Comments about Evolution as an Alternative to Thunderbird

Michel Th.
I use both Thunderbird and Evolution, sometimes Claws-Mail. Evolution is the only one that can show the real "received" date in scams I have been receiving for months. In a today's scam Evolution shows "sent date" (falsified) 14-12-2019 and "received date" 30-01-2023 (evidently true). Thunderbird and Claws-Mail show 14-12-2019 in both columns.
Positive comment •Jan 30, 2023
1
Guest
well, I use cinnamon desktop, Thunderbird does not display 24 hour format but AM/PM for starters. Also, I use the built-in acount manager and Thunderbird does not "talk" with that as well.. Evolution does sync my CALDAV and CARDDAV from this. Thunderbird needs plugins for this and these plugins also make Thunderbird unstable (lightning). Since I like to keep things "clean", Evolution is my software of choice ATM...
Positive comment •Dec 20, 2019
1
Syntevo GmbH
Unfortunately, only available on Linux, not on Windows, not on MacOS. Otherwise promising.
Comment •Nov 18, 2022
0
Guest
Has a nice Gui, works fast and has many options. Still some functions are not intuitive. Good alternative to Thunderbird
Positive comment •Apr 16, 2021
0
- Most users think Evolution is a great Thunderbird alternative.
- Evolution is Free and Open SourceThunderbird is also Free and Open Source

SeaMonkey
Web-browser, advanced e-mail, newsgroup and feed client, IRC chat, and HTML editing in one application. Itis built on the open source Mozilla Gecko engine, the same code which underlies Thunderbird and is the base for the Firefox browser.
244 SeaMonkey alternatives
License model
- Free • Open Source
Application types
- Web Browser
- Email Client
Platforms
- Mac
- Windows
- Linux
- BSD
- PortableApps.com
+3
Top SeaMonkey Features
1. Integrated Email Client
2. Built-in RSS reader
3. Add-ons
4. Customizable
5. Built-in Download Manager
6. Lightweight
7. WYSIWYG Support
8. Extensible by Plugins/Extensions
9. Portable
10. Privacy focused
11. Ad-free
12. Support for Firefox extensions
Show all NaN SeaMonkey features ▾
SeaMonkey VS Thunderbird
Is SeaMonkey a good alternative to Thunderbird?
Comments about SeaMonkey as an Alternative to Thunderbird

Guest
SeaMonkey is both a WEB BROWSER and EMAIL CLIENT. It's the successor of Mozilla Application Suite or Netscape Communicator, resp. Further it includes also a news client program, an HTML editor (SeaMonkey Composer) and an IRC client (ChatZilla).
Positive comment •Nov 16, 2017
21
apostolfaliagas
It has all of Thunderbird's features and many more.
Positive comment •Feb 19, 2018
15
Guest
Unfortunately doesn't support synchronization with CardDAV address books.
Negative comment •Mar 28, 2022
0
Guest
More of a web browser than an email client
Negative comment •May 12, 2019
-9
- Some users think SeaMonkey is a great Thunderbird alternative, some don't.
- SeaMonkey is the most popular Mac alternative to Thunderbird.
- SeaMonkey is Free and Open SourceThunderbird is also Free and Open Source
- SeaMonkey is Lightweight and Privacy focusedThunderbird is not according to our users

Geary
Geary is an email application built around conversations, for the GNOME 3 desktop.
50 Geary alternatives
License model
- Free • Open Source
Application type
- Email Client
Platforms
- Linux
- BSD
- Flathub
- GNOME
- Flatpak
Top Geary Features
1. Multiple Account support
2. Conversational email approach
3. Dark Mode
4. Gmail integration
5. IMAP Support
6. Lightweight
7. Spam Filter
8. Ad-free
9. Email Organizer
10. Privacy focused
11. Labels for content
12. SMTP Support
Show all NaN Geary features ▾
Geary VS Thunderbird
Is Geary a good alternative to Thunderbird?
Comments about Geary as an Alternative to Thunderbird

Kelson V
Geary is a lot lighter than Thunderbird, so it's a good choice on lower-end hardware. IMAP features are basic, but 90% of what most people will need. It relies on GNOME for contacts, but the mail app itself can run on any Linux desktop.
Positive comment •Nov 28, 2023
0
Guest
Doesn't have an address book
Negative comment •Apr 23, 2017
1
Guest
Only IMAP. No support for local folders.
Negative comment •Sep 28, 2018
1
Guest
Easy to set up. Thunderbird doesn't connect anymore with hotmail and yahoo. No address book.
Positive comment •Jul 18, 2017
-21
- Most users think Geary is a great Thunderbird alternative.
- Geary is Free and Open SourceThunderbird is also Free and Open Source
- Geary is Lightweight and Privacy focusedThunderbird is not according to our users

Betterbird
Betterbird is a drop-in replacement for Mozilla Thunderbird. Betterbird has more features and more fixed bugs than Thunderbird.
28 Betterbird alternatives
License model
- Free • Open Source
Application types
- Email Client
- Calendar App
Platforms
- Mac
- Windows
- Linux
- Flathub
- Chocolatey
+8
Top Betterbird Features
1. Multiple Account support
2. Privacy focused
3. Lightweight
4. Extensible by Plugins/Extensions
5. Unified inbox
6. Works Offline
7. Ad-free
8. Support for Themes
9. Portable
10. PGP Encryption
11. No Tracking
12. Spam Filter
Show all NaN Betterbird features ▾
Betterbird VS Thunderbird
Is Betterbird a good alternative to Thunderbird?
Comments about Betterbird as an Alternative to Thunderbird

Sam Lander
Betterbird does everything that Thunderbird does (it's a soft fork), while improving bugs and features.

Because it's a soft fork, it retains the security implementations of Thunderbird.

Thunderbird actually implements many of the bug fixes created by Betterbird, but at a much slower pace.
Positive comment •May 31, 2023
2
HOT EARTH
Its Thunderbird, just Better. No Import needed, as it uses the same profile Folder!
Positive comment •Sep 5, 2022
4
Guest
It has many fixes for long existing bugs
Positive comment •Jun 20, 2024
1
Guest
No Thunderbird importation.
Negative comment •Sep 9, 2021
-6
- Most users think Betterbird is a great Thunderbird alternative.
- Betterbird is Free and Open SourceThunderbird is also Free and Open Source
- Betterbird is Privacy focused and LightweightThunderbird is not according to our users

Mailspring
Boost your productivity and send better email with Mailspring, a beautiful, fast email client for Mac, Windows, and Linux. Mailspring is free to use and an optional pro version adds read receipts, send later, reminders and more.
43 Mailspring alternatives
License model
- Freemium • Open Source
Application type
- Email Client
Platforms
- Mac
- Windows
- Linux
- Arch Linux
- Fedora
- Ubuntu
+1
Top Mailspring Features
1. Unified inbox
2. Multiple Account support
3. Dark Mode
4. Customizable
5. Email tracking
6. User friendly
7. Snooze Mail
8. Ad-free
9. Theme Customization
10. Support for Themes
11. Email Organizer
12. Extensible by Plugins/Extensions
Show all NaN Mailspring features ▾
Mailspring VS Thunderbird
Is Mailspring a good alternative to Thunderbird?
Comments about Mailspring as an Alternative to Thunderbird

3psilon
Great alternative, especially for casual users. Simple, streamlined UI, feels fresh.
Top positive comment •May 2, 2018
1
Riska Asmara
Simple, more streamlined UI and easily customizable.
Top positive comment •Feb 1, 2019
4
Guest
Need to create an account on a third-party company to access your email.
Top negative comment •Sep 28, 2018
59
Matt Schaefer
Unable to even find an address book or ability to import a csv file from previous mail client. You lose me when things are made so "modern-clean" that I have to consult a manual or Google things.
Negative comment •Jul 15, 2022
0
Peter Bromfield
nice interface (if you are talking about the feature, kcontact/kmail is the best, but this has a nice interface)
Positive comment •Feb 20, 2018
-3
Show more comments
5 of 7 comments
- Most users think Mailspring is a great Thunderbird alternative.
- Mailspring is Freemium and Open SourceThunderbird is Free and Open Source