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Shredder Alpha 2
Release Notes

Released: August 12, 2008

Shredder Alpha 2 is a developer preview release for the next major version of Thunderbird that is being built on top of the next generation of Mozilla's layout engine, Gecko 1.9. Shredder Alpha 2 is being made available for testing purposes only and is intended for developers and our testing community.

This release does not represent the final product. Some of the features listed below are highly experimental and will likely change before the final release. They may come with crashes and bugs and may potentially cause data loss in profiles (configuration data, preferences, downloaded mail).

Please do not use Shredder Alpha 2 in a production environment.

Please see below for a list of features and enhancements found in Shredder Alpha 2, as well as known issues and frequently asked questions. As always, we appreciate your feedback either through this feedback form or by filing a bug in Bugzilla.

What's New in Shredder Alpha 2

There were over 300 bug fixes in this release, many laying the groundwork for future changes. Some notable changes include:

Integration improvements
  • Shredder can import mail from on Mac OS X
  • Shredder theme looks more native on OS X
  • OS X Address Book integration on by default
  • Improved accessibility for screen readers
  • Outlook Express import now copies SSL and port settings
Other features
  • IMAP delete and undo operations are faster
  • Forwarded messages are inline by default
  • Replies allow to quote only selected text
  • Purge button added to toolbar optionally
Platform improvements
  • Extension authoring made easier by assigning IDs to most XUL elements
  • Windows x64 builds now possible
  • Several improvements to junk scoring subsystem

For a more detailed list of bug fixes, see the Rumbling Edge.

Downloading and Installing

System Requirements

Before installing, make sure your computer meets the system requirements.

Please note that Shredder Alpha 2 no longer supports versions of Windows prior to Windows 2000 (e.g. Windows 95, 98, ME and NT) and Mac OS X versions prior to 10.4 Tiger. Linux requirements have also changed. Do ensure that compatibility mode for unsupported Windows platforms is disabled for the Thunderbird executable in Windows.

Downloading Shredder Alpha 2

Mozilla Messaging provides Shredder Alpha 2 for Windows, Linux, and Mac OS X in a variety of languages. You can get the latest early release of Shredder/Thunderbird here.

Installing Shredder Alpha 2

Please note that installing Shredder Alpha 2 will overwrite your existing installation of Thunderbird on Windows, Linux and Mac OS X. For all systems, you won't lose any of your messages or address books, but some of your extensions and other add-ons might not work until updates for them are made available.

Users are highly encouraged to install Shredder Alpha 2 in another folder (on Windows, this is done using Custom Install) and backup their profiles before testing Shredder Alpha 2.

Removing Shredder Alpha 2

You can remove Shredder Alpha 2 through the Control Panel in the Start Menu on Windows, by removing the Thunderbird application on OS X, or by removing the thunderbird folder on Linux.

Removing Shredder Alpha 2 won't remove your emails or newsgroup messages. This data is stored in your profile folder, which is located in one of the following locations depending on your operating system:

Windows Vista Users\<UserName>\AppData\Roaming\Thunderbird
Windows 2000, XP, Server 2003 Documents and Settings\<UserName>\Application Data\Thunderbird
Mac OS X ~/Library/Thunderbird
Linux and Unix systems ~/.thunderbird

Any version of Thunderbird that you install after removing Shredder Alpha 2 will continue to use the data from this profile folder.

Extensions and Themes

Extensions installed under previous versions of Thunderbird may be incompatible and/or require updates to work with Shredder Alpha 2. Please report any issues to the maintainer of the extension.

When you install Shredder Alpha 2 all of your Extensions and Themes will be disabled until Shredder Alpha 2 determines that either a) they are compatible with the Shredder Alpha 2 release or b) there are newer versions available that are compatible.

Known Issues

This list covers some of the known problems with Shredder Alpha 2. Please read this before reporting any new bugs.

All Systems
  • There will not be any automatic updates to this developer preview.
  • Ensure extensions either come from a secure server using the HTTPS protocol or are digitally signed, or they will fail to install.
  • The "Move To" sub-menu is empty (bug 432088)
Microsoft Windows
  • Make sure Windows 95/98 compatibility mode is disabled for the Thunderbird executable. The setting will be inherited from previous Thunderbird installations if the original directory is over-written. Certain issues will go away once the compatibility mode is disabled. (Bug 381922)


  • Poorly designed or incompatible extensions can cause problems with your email client, including make it crash, slow down message display, etc. If you encounter strange problems relating to parts of the email client no longer working, the email client not starting, windows with strange or distorted appearance, degraded performance, etc, you may be suffering from Extension or Theme trouble. Restart the email client in Safe Mode. On Windows, start using the "Safe Mode" shortcut created in your Start menu or by running thunderbird.exe -safe-mode. On Linux, start with ./thunderbird -safe-mode and on Mac OS X, run:

    cd /Applications/
    ./thunderbird-bin -safe-mode

    When started in Safe Mode all extensions are disabled and the Default theme is used. Disable the Extension/Theme that is causing trouble and then start normally.
  • If you encounter strange problems relating to email, feeds or newsgroup messages, it is recommended that you try creating a new profile and attempting to reproduce the problem before filing bugs. Create a new profile by running Thunderbird with the -P command line argument, choose the "Manage Profiles" button and then choose "Create Profile...". Migrate your settings files (Emails, feeds, etc) over one by one, checking each time to see if the problems resurface. If you do find a particular profile data file is causing a problem, file a bug and attach the file, being sure to remove any private information as necessary.

Frequently Asked Questions

  1. What can I do to help?

    We need help from developers and the testing community to provide as much feedback as possible to make Thunderbird even better. Please read these notes and the bug filing instructions before reporting any bugs to Bugzilla.

  2. Where can I discuss Shredder alpha features or issues?

    If you want to join the conversations about new features or need troubleshooting advice, check out the MozillaZine forums. You can also post questions in the "" newsgroup, available on Mozilla's news server, or via the web, using Google Groups. It is also available as a mailing list. Please read the Mozilla Forum Etiquette page before posting.

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

    Extensions and Themes can be downloaded from Thunderbird Add-ons.

    Note that because this is an early alpha, most add-ons won't be compatible with it until the add-on developer explicitly upgrades their add-on.

  4. Who makes Shredder Alpha 2?

    Many people! Mozilla Messaging is the organization that produces it, but it is the result of collaboration between hundreds of people around the world.

  5. Where's the Shredder Alpha 2 source code?

    A tarball of the Shredder Alpha 2 source code is available for download. The latest development code can be obtained by cvs. Thunderbird-specific source is in "mozilla/mail", "mozilla/toolkit", and "mozilla/chrome". Please follow the build instructions.

The following resources contain useful information about Shredder Alpha 2: