Whether you are just curious or already using beta, this reference will help you have the best possible experience. Beta is a great choice if you want to help the global Thunderbird community and product by testing fixes and new features, and discovering and reporting bugs before they reach release. Thank you for your interest in using beta!

README BEFORE using beta

• Protect your Thunderbird data by doing regular backups of your Thunderbird profile.
• High-impact flaws such as data loss are rare but may occur. Protect yourself with backups.
• New features require new code, so flaws are possible. Flaws may not be fixed quickly because of competing priorities, but do report them. Do remember that patience is required when using test versions.
• Use the beta topicbox to learn about new features and user experience.
• Expect frequent updates, so that we can provide improvements quickly.
• Make sure your installer does not install beta in a non-beta program directory - official Mozilla downloads should do this correctly. See How to install and run Beta for more information.
• If you use Thunderbird mail filters and you have more than one Thunderbird data profile, decide where you want to run your filters - in your beta profile or your other profile. Do not use filters in both.
• Add-on authors are not obligated to make their add-ons work in beta. As a result, some of your add-ons may not work in beta. Please submit your issues to the add-on author, and consult the Add-ons FAQ if you have difficulty.
• Are you using POP accounts? Unlike IMAP accounts, your only copy of POP mail is in your local Thunderbird data profile and not on a server (unless you changed the default settings). To use a POP account with beta you must choose between these choices:
  • Don't use a POP account with your beta or daily install: Using POP is not recommended because you risk losing your email if you do not configure ALL of your email clients correctly with your POP accounts.
  • If you have to use POP:
    1. Set all of your email clients including Thunderbird for Android and Thunderbird Desktop, Outlook, etc. to Leave messages on server in ≡ > Account Settings > Server Settings (or equivalent in your email clients).
    2. Uncheck For at most [X] days.
    3. Manually delete messages from the POP server. We recommend you do not use Fetch headers only or equivalent in your non Thunderbird email clients.

Resources, assistance and references

How you can help improve Thunderbird, find help, and give help:

• Review the README above.
• Post questions about normal Thunderbird usage in Thunderbird support aka SUMO.
• Answer questions about Thunderbird usage in SUMO.
• Ask and help with beta-specific questions in the beta topicbox community.
• Report bugs that you find. Report performance issues by creating a performance profile and adding it to your bug report or support posting.
• Read informative Release Notes at ≡ > Help > About Thunderbird Beta > Release Notes in Thunderbird, or visit Beta release notes.
• Submit all crash reports.
• Backup your profile with ≡ > Tools > Export.
• Review the Beta Start Page which has handy information, accessed in Thunderbird with ALT > Go > Mail Start Page (keyboard shortcuts), or in your browser.
• Join us in other ways to contribute to the project.

Add-ons

Add-on authors are not obligated to have their add-ons work in beta. Some might not work. Consult the add-ons FAQ if you have difficulty.

How to install and run beta

Install Thunderbird Beta into its own program directory. If you download beta from official sources, then installation should happen correctly. Do check that it installs to its own program directory, for example C:\Program Files\Mozilla Thunderbird Beta. If you need more help please refer to installation instructions for Windows, macOS, Linux, and official sources for additional details.

Quick links to official beta sources:

• Windows, macOS and Linux via Thunderbird download page - choose the beta channel
• Ubuntu from Canonical via Snap -- sudo snap install thunderbird --beta
• Flatpak

How do I change from a beta version back to a release version?

Do not change from beta to release by installing release into the beta program folder, nor by pointing a release install to a Thunderbird beta data profile - accessing data with an older version number of the program risks instability and corrupt data.

Instead, make a separate profile for release, and transfer any data you need from the beta profile using standard tools address book export+import, for example Address Book Export/Import, or ≡ > Tools > Export. Exceptions:

• For POP and local mail: In the Mail directory of your Thunderbird profile you will find both Local Folders directory and POP account directories. You can copy the contents of these from one profile to another, but take care to NOT overwrite any msgFilters.dat files as they contain your filter rules. HOWEVER, NOTE, files from a newer version are not guaranteed to work in an older version.
• For IMAP accounts, there should be no need to copy any files from a beta profile to your production profile.

Beta isn't for me. How can I help?

Participate lists many ways for you to help in the community, and places to learn more about Thunderbird.