Thunderbird 5.0 - New Features and Changes

This is a draft and work in progress. Please add comments and suggestions to the discussion page.

• This article is inherently incomplete and subject to change until TB 5.0 is released.
• Make sure you understand that pre-release versions may be stable enough for your purpose but equally well may corrupt your e-mail or entire system when running into bugs!
  • Do not use pre-release versions in production environments where data loss or instability matters!
  • See Testing pre-release versions on how to stay on the safe side before looking into the release candidates.

Thunderbird 5.0 has just issued its first beta release and the final release is coming up soon! Don't be fooled by the version number. While the changes from 2.0 to 3.0 were substantial, this is a rather incremental release, comparable to 3.1 versus 3.0. Thus, Everything in Thunderbird 3.1 - New Features and Changes and also Thunderbird 3.0 - New Features and Changes should still be valid unless obsoleted here.

What happened to Thunderbird 4.0?

In a process driven by the Firefox developers, Mozilla has substantially redesigned their release process. Thus, there will no longer be parallel branches after Firefox 3.6 and Thunderbird 3.1 have reached their end of support. Instead, each release will have a full version bump even if there are no or marginal feature changes (i.e., Firefox 5.0 will be the stability update for 4.0.1, then 6.0 will be the update for 5.0, etc.) [1]. Only in quick "firedrill" follow-up releases which become necessary shortly after a release to fix a missed issue, a minor "dot" release will be issued.

Thunderbird decided to follow that pattern, and in the process re-aling its numbers with Firefox again [2]. Consequently, the "Miramar" branch has been bumped from 3.3 to 5.0, and the next release after 5.0 will be Thunderbird 6.0 around the same time when Firefox 6.0 is released. It yet has to be seen how this process turns out in practical terms, especially with respect to add-on compatibility as a stable API is no longer given as it was previously assured during the lifetime of a branch.

Changes in supported platforms

There are no changes in support on Windows, the minimum platform remains Windows 2000 and only 32-bit builds are available [3]. On Mac OSX, support for 10.4 is discontinued, and the PPC platform (G3, G4, G5) is no longer supported. Instead, the universal downloads contain both 32-bit and (new) 64-it versions. Linux requirements are the same as for 3.1, by default you will get the 32-bit version from the download page, official 64-bit builds are available from the release server for manual download [4].

New appearance on Vista and Windows 7

New default theme

While the "aero" theme has received a major overhaul [5], only moderate updates have been made to the themes on the other platforms, including the Windows XP/2000 theme. See Thunderbird 5.0 - New Features and Changes/Themes for a detailed discussion on the changes on Vista and Windows 7.

There has be a redesign of the addressing area in the composition window on all platforms [6]. As the most visible change, the "To", "Cc", ... selector buttons are no longer part of the address block but appear as "true" menu buttons to the left of it.

On Linux, the default theme uses several GTK stock icons, i.e., they aren't included with the Thunderbird default theme. You may see error messages in your console window that icons are missing, and those may not display properly when Thunderbird is running. Thus, make sure that the relevant GTK libraries are installed. Using a re-packaged Thunderbird version from your distribution's repository may avoid any such conflicts, but beta versions may not be available.

Font rendering issues

Most platform perform font smoothing by default to achive a better rendering on LCD screens. Depending on your personal preferences or needs, different settings may work better for different users, thus it's a bit of try and error to find the optimum settings. In general, this applies equally to all applications and isn't unique to Thunderbird.

Like Firefox 4.0 and later, Thunderbird 5.0 supports Direct2D font rendering on Windows [7]. You can check in Help → Troubleshooting Information, Graphics section at the very bottom, if it is available on your platform (look for "Direct2D Enabled") along with possible hints, e.g., on an outdated driver. This feature is related to but separate from the ClearType settings [8] which can be found (on Windows 7) in the Display section of the Control Panel ("Adjust ClearType text").

If the fonts look blurred to you and don't improve with tweaking the ClearType settings, change gfx.direct2d.disabled to "true" and restart Thunderbird to see if it makes any difference.

Account setup

New account wizard

[9]

Archiving can be disabled

[10]

• mail.identity.default.archive_enabled
• mail.identity.default.archive_granularity
• mail.identity.default.archive_keep_folder_structure

Attachment pane redesign

[11], [12], [13]

Show first row of attachments only by default, then allow opening with toggle:

#attachmentView > [collapsed="true"] {
  visibility: visible !important;
  overflow: auto !important;
}

Always open, toggle removed:

#attachmentView > [collapsed="true"] {
  visibility: visible !important;
}

#attachmentToggle {
  display: none !important;
}

Advanced options

Signature delimiter

mail.identity.default.suppress_signature_separator [14], [15]

Display of large message/attachment sizes

chrome%3A//messenger/locale/messenger.properties#megaByteAbbreviation2=***%.*f MB

New add-ons manager

extensions.getAddons.cache.enabled [16]

Privacy considerations

Phoning home

• extensions.blocklist.enabled
• extensions.getAddons.cache.enabled [17]
• extensions.getAddons.get.url [18]
• mail.instrumentation.askUser [19]
• mail.instrumentation.postUrl

See also

• Thunderbird 5.0 - New Features and Changes/Themes - new default theme for Windows 7 and Vista, collected userChrome.css examples.
• Thunderbird 3.1 - New Features and Changes, Thunderbird 3.0 - New Features and Changes - previous (and mostly still valid) articles in this series.