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Thunderbird

Free, open-source desktop email client from Mozilla

Thunderbird is a free and open-source email client for Windows, macOS and Linux, with an Android app based on K-9 Mail. It manages multiple accounts in a unified inbox and includes a calendar, address book, chat and built-in OpenPGP encryption. Add-ons and themes customize it extensively, and it is developed by MZLA Technologies, a Mozilla Foundation subsidiary funded by user donations.

Cost / License
FreeOpen source(MPL-2.0)
Categories
Email Clients & Providers
Platforms
WindowsMacLinuxAndroid
Thunderbird screenshot
Thunderbird alternativesVisit website
features
6
alternatives
9
platforms
4
Updated
Oct 12, 2026

Features

Our take

Pros

  • Free and open source, funded by donations rather than ads
  • Built-in OpenPGP encryption, calendar and address book
  • Highly customizable with add-ons and themes

Cons

  • Interface feels busier than minimalist modern clients
  • Getting the most out of it takes some setup and add-ons

Editorial assessment by the Alternatives.tools team, based on what the product is known for. Not a user review.

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