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Thunderbird Release Notes

Thunderbird is a full-featured email, RSS and newsgroup client that makes emailing safer, faster and easier than ever before. More information about Thunderbird is available.

These Release Notes cover what's new, download and installation instructions, known issues and end user support / feedback for the Thunderbird 1.5 Beta 2 release. Please read these notes and the bug filing instructions before reporting any bugs to Bugzilla.

We want to hear your feedback about Thunderbird. Please join us in the Mozilla Thunderbird Support forum, hosted by MozillaZine.

What's New in Thunderbird 1.5 Beta 2

Thunderbird 1.5 Beta 2 is a preview of our award-winning email client. Thunderbird 1.5 Beta 2 is for our early adopter community, and our Extension developers.

Here's what's new in Thunderbird 1.5 Beta 2:

  • Automated update to streamline product upgrades. Notification of an update is more prominent, and updates to Thunderbird may now be half a megabyte or smaller. Updating extensions has also improved.
  • Sort address autocomplete results by how often you send e-mail to each recipient.
  • Spell check as you type.
  • Built in phishing detector to help protect users against email scams.
  • Podcasting and other RSS Improvements.
  • Deleting attachments from messages.
  • Integration with server side spam filtering.
  • Reply and forward actions for message filters.
  • Kerberos Authentication.
  • Auto save as draft for mail composition.
  • Improvements to product usability including redesigned options UI, and SMTP server management.
  • Many security enhancements

Downloading and Installing

System Requirements

Before installing, make sure your computer meets the system requirements. Starting with 1.5, Mac OS X users must have Mac OS X 10.2 or greater.

Downloading Thunderbird 1.5 Beta 2

The Mozilla Foundation provides Thunderbird for Windows, Linux, and Mac OS X.

Windows: Installer

Linux: GTK2 + XFT (no installer)

Mac OS X: Compressed Disk Image

For builds for other systems and languages not provided by, see the Contributed Builds section at the end of this document.

Installing Thunderbird

Once you have downloaded a Thunderbird installer or compressed archive, follow these instructions to install:


Double click the Thunderbird Setup 1.5 Beta 2.exe installer to start the install.


Once you have downloaded the Thunderbird 1.5 Beta 2.dmg file, double click the Thunderbird Disk Image to open it in Finder, and then drag the Thunderbird application onto your hard disk. Drag the icon to your Dock if you want it to appear there.

Other Platforms

Extract the compressed archive and run thunderbird

Uninstalling Thunderbird

To uninstall Thunderbird, follow these instructions:


From the Start menu, choose Control Panel. When the Control Panel appears, double click Add/Remove Programs. Find "Mozilla Thunderbird (1.4.1)" in the list and click Remove to uninstall.


Drag the Thunderbird application to the Trash.


Remove the thunderbird folder.

These instructions leave your profile in place in case you install Thunderbird again in the future. If you wish to remove your profile folder, remove the location described below in the "Profile Folder" section. Note that by doing this you are destroying all of your email, address book data, settings and other information and should you decide to use Thunderbird again you will be starting with a clean profile.

Other Information

Profile Folder

Thunderbird stores your user data in one of the following locations:

Windows 2000, XP Documents and Settings\<UserName>\Application Data\Mozilla Thunderbird
Windows NT WINNT\Profiles\<UserName>\Application Data\Mozilla Thunderbird
Windows 98, ME Windows\Application Data\Mozilla Thunderbird
MacOS X ~/Library/Thunderbird
Linux and Unix systems ~/.thunderbird

Known Issues

This list covers some of the known problems with Thunderbird 1.5 Beta 2. Please read this before reporting any new bugs, and watch it regularly (we'll update it as new bugs are found in the release).

Extensions and Themes

Extensions installed under Thunderbird 1.0 may be incompatible and/or require updates to work with Thunderbird 1.5 Beta. Please report any issues to the maintainer of the extension. When you install Thunderbird 1.5 Beta all of your Extensions and Themes may be disabled until Thunderbird 1.5 Beta determines that either a) they are compatible with the 1.5 Beta release or b) there are newer versions available that are compatible. This is because Thunderbird changes from release to release and as such the ways in which some extensions integrate changes, meaning there can be problems when running an older extension with a newer version of Thunderbird. If you find that your favorite Extension or Theme has not been updated to be compatible with this release of Thunderbird, write the author and encourage them to update it.

All Systems

  • Prior to installing Thunderbird 1.5 Beta 2, please ensure that the directory you've chosen to install into is clean and doesn't contain any previous Thunderbird installations.
  • If you install Thunderbird on a multi-user system in an area in which there is restricted access privileges, you must run Thunderbird as a user with access to that location upon installation so that all initial startup files are generated. If this is not done, when a user without write access to the install location attempts to start Thunderbird, they will not have sufficient privileges to allow Thunderbird to generate the initial startup files it needs to.
  • When upgrading, all your Extensions and Themes will be disabled. This is not an issue, but it may appear to be one (hence its listing here). For rationale, see "Extension and Themes" above.
  • The default dictionary is English-only. To add a non-English dictionary, read the installation instructions.
  • When switching between using a Global Inbox and using an Inbox for a POP3 account, be sure to make copies of the messages into another folder.
  • Software Update will not work if Thunderbird is installed to a location that you do not have write access to, since Software Update needs to replace or create files in this location.


  • When installing as a restricted access user on a shared machine into a location that you can write to, there may still be negative side effects (default email/other keys not being set correctly). The email client should still function however. When installing as a restricted access user do not attempt to install over an installation in a restricted-access/shared location as this may destroy that installation.
  • Windows users can sync their address book with a Palm device by installing the Palm Sync extension for Thunderbird. Save the file locally and install it from the extensions dialog in Thunderbird. The extension will not show up in the list of extensions. You will have to restart Thunderbird after installing the extension before it will take effect.


  • Do NOT run Thunderbird from the Disk Image! - doing this will cause an infinite restart loop (the symptom of which is a Thunderbird icon that bounces briefly in the Dock then disappears and reappears, bounces and disappears, over and over). To break Thunderbird out of this loop, open a Terminal and type "killall thunderbird-bin" and press enter. Install Thunderbird to a location you have write access to and try again. When installing on a multi- user limited access system, install it into a shared location as administrator, run it once and then all users should be able to access it.

Linux and Unix systems

  • GNOME integration does not work properly with Fedora Core 3. Users of Fedora Core 3 will need to download and install linc-1.0.3-3.1.i386.rpm. After installing the RPM, perform the following command in the directory you installed Thunderbird into (you will need write permission):

    touch .autoreg

    The next time you start Thunderbird, GNOME integration should be functional.


Frequently Asked Questions

  1. What can I do to help?

    We need all the exposure we can get. Make it your mission to convert as many of your friends, family members and coworkers as possible. If you're a student, get it distributed at your college. Submit a story to Slashdot and other news sites about the release. Make some noise on your blog. Mass distribution via the Internet is possible -- look at Kazaa.

  2. Why haven't you responded to the mail I sent you?

    Use the forums. The Thunderbird team reads them regularly. We all get a lot of email and your email may get lost.

  3. Where can I get themes and add-ons (extensions)?

    Extensions and themes can be downloaded from Mozilla Update.

  4. Who is working on Thunderbird?

    Lots of people. See Help->About Mozilla Thunderbird, Credits for a list of some of the people who have contributed to Thunderbird.


The following resources contain useful information about Thunderbird:


Contributed Builds

These are unofficial builds and may be configured differently than the official builds. They may also be optimized and/or tested for specific platforms.

Solaris(Contributed by SUN Beijing team)

Other Systems

Builds for platforms other than the trio officially offered by can be found on the FTP site.

Localized Builds

Many localized builds are now produced and distributed by on behalf of their authors. View All Systems and Languages to see the set of builds that we offer.

Previous versions of the Release notes: 0.1 | 0.2 | 0.3 | 0.4 | 0.5 | 0.6 | 0.7 | 0.8 | 0.9 | 1.0 | 1.0.2 | 1.0.5 | 1.0.6 | 1.0.7