As a general warning for anybody running early or pre-releases, bad things can happen, especially when using the nightly builds which reflect a snapshot of the current development. To recall a couple of hints:
- Use pre-release versions only for data where you don't mind loosing them;
- don't use the same profile for testing and release versions;
- regardless of whether you are using nightlies or stable releases, having regular backups of a profile is the key to recovery from a disaster;
- for IMAP accounts, I'm also backing those up locally with a release version, in case the remote folders get wiped out.
Rapid-Release Model:
Thunderbird followed Firefox implementing rapid-release scheme for Thunderbird 5.0 and later. The core of this scheme is that no longer parallel branches exist, thus comm-miramar (for 5.0) will be the last branch-specific repository. Instead, four "channels" were introduced, replacing the current release repositories:
Thus, the releases starting with 6.0 went into comm-release/mozilla-release at the time of release. The next release is in comm-beta/mozilla-beta, and the next after that in comm-aurora/mozilla-aurora. Development itself remains on comm-central and mozilla central, where approved patches can go into the aurora or both aurora and beta channels. Changes on the release channel are only made in case of a quick "firedrill" release, requiring a "dot" update with just that fix applied.
Starting with 17.0, mainstream releases come from the ESR branch explained in the next section (i.e., 17.0.x until 24.0 is reached and a new branch opened). At that time, the regular releases switch to 24.0 whereas ESR releases stick with 17.0 for two more cycles.
Discontinuation of the aurora channel:
Note that after the 52.0 cycle, both mozilla-aurora and comm-aurora have been discontinued. For 55.0 and following, mozilla-central and comm-central will directly merge into comm-beta, thus shortening each cycle by 6 weeks:
Special Extended Support Releases:
There have been objections from the enterprise community that no longer stable branches are provided after 3.1.x reaches end of life. Corporations, institutions, or other organizations may have requirements to certify software before deploying it, then assuming a branch to be stable, which is no longer applicable with the rapid-release system.
Starting with Thunderbird 10.0, special ESR builds are offered which are frozen for any feature work but will receive security updates as "dot" releases (i.e., 10.0.1 ESR would have the major security fixes as 11.0, then 10.0.2 ESR matching 12.0, etc.). These builds are primarily directed towards enterprise users and organizations to accommodate their needs for software certification. Also "regular" users can utilize those if they prefer a stable user experience for a while rather than new features coming in as quickly as they are developed.
These builds come from their own comm-10esr/mozilla-10esr repositories, similar to the legacy branches. New ESR branches are scheduled to be opened roughly once a year (thus, 7 rapid-release cycles), the next branch being due with the regular 17.0 release and 10.0.x ESR reaching EOL with 17.0.2 ESR.
- Official start page for ESR builds:
http://www.mozilla.org/en-US/thunderbird/organizations
The comm-17esr/mozilla-17esr repositories are now in place and will be used for both regular and ESR releases starting with 17.0.3. If there should be an intermediate release to get out new features earlier than with the next (24.0) ESR cycle, there may be a regular 17.1 release, in which case ESR releases should continue to come from the 17.0 branch anyway.
Starting with 24.0, there are no longer dedicated ESR releases for Thunderbird. Instead, the retail build from comm-esr24/mozilla-esr24 will be the only ones generated, and updates from 17.0.11 ESR will go to 24.2.0 retail version. It is unclear at this time if a 2-cycle overlap between 24.0 and 31.0 will be maintained.
Download locations of nightly builds:
Naturally, the trunk "nightly" builds have the largest volatility and may be broken at any time by a recent check-in. On the other hand, those reflect the most recent new features and bug fixes. After some "baking" time, such patches can go into the "aurora" and possibly "beta" channels, as long as they don't have any API changes or need string translations (thus to give localizers sufficient time).
Regular builds are only offered for "Daily" (nightly channel) and "Earlybird" (aurora channel). "Beta" builds are created after a couple of changes checked in and officially released, usually in weekly intervals leading up to a release. After each release, current "Daily" versions move into "Earlybird", which in turn moves into "Beta". The version you've initially downloaded retains its configured update channel, thus you will see an explicit version bump at that time.
- Earlybird nightlies (next after beta): comm-aurora/mozilla-aurora (discontinued)
http://ftp.mozilla.org/pub/mozilla.org/thunderbird/nightly/latest-comm-aurora/
http://ftp.mozilla.org/pub/mozilla.org/thunderbird/nightly/latest-comm-aurora-l10n/
- Daily trunk nightlies (was Shredder): comm-central/mozilla-central
http://ftp.mozilla.org/pub/mozilla.org/thunderbird/nightly/latest-comm-central/
http://ftp.mozilla.org/pub/mozilla.org/thunderbird/nightly/latest-comm-central-l10n/
Download locations for beta-channel release builds and candidates:
In general, those are located in the thunderbird/nightly folder as well before moved to the release folder and its mirrors. For automated updates, set your update channel to beta, then you'll get an update offer once the builds are done and have passed an initial brief review.
For Windows, ZIP installers are only available for nightly builds and release candidates and located in the "unsigned" folder.
- Official download page for aurora and beta builds:
http://www.mozilla.org/en-US/thunderbird/channel
With the switch to build mainstream releases also from the ESR repositories, only one beta during each cycle is planned until close to the opening cycle for a new ESR branch.
Download locations for Lightning calendar:
- For nightly builds from the aurora channel:
http://ftp.mozilla.org/pub/mozilla.org/calendar/lightning/nightly/latest-comm-aurora/
- For nightly builds from the nightly trunk channel:
http://ftp.mozilla.org/pub/mozilla.org/calendar/lightning/nightly/latest-comm-central/
- For beta and release channels:
https://addons.mozilla.org/thunderbird/addon/lightning/versions/
- up to TB 17.0, Lightning 1.x should be used for Thunderbird y.0, with x = y-8 (i.e., 1.0 for TB 8.0, 1.1 for 9.0, 1.2 for 10.0, etc.);
- for TB 18.0 and later, Lightning 2.x should be used for Thunderbird y.0, with x = y-18 (i.e., 2.0 for TB 18.0, 2.1 for 19.0, 2.2 for 20.0, etc.).
- for TB 28.0 and later, Lightning 3.x should be used for Thunderbird y.0, with x = y-28 (i.e., 3.0 for TB 28.0, 3.1 for 29.0, 3.2 for 30.0, etc.).
- the TB 24.x.y releases need Lightning 2.6.z, the upcoming TB 31.x.y releases should need Lightning 3.3.z, with z being increased for any regular cycle x and potentially any "firedrill" release y.
Legacy branches:
The last active stable branch following the old model with nightly builds is Lanikai (3.1.x), reflecting current security and stability updates going towards its next minor "dot" release (see this page for a listing of currently active branches). The Miramar (5.0) nightly builds have stopped as this release already follows the new rapid-release scheme, despite having its own repositories:
- Obsolete stable 2.0.0.x and earlier branches: cvs
(no nightly builds are available any more for these versions, no more updates)
- Obsolete stable 3.0.x branch (l10n = localized versions): comm-1.9.1/mozilla-1.9.1
(no nightly builds are available any more for these versions, no more updates)
- Discontinued stable 3.1.x branch (Lanikai, Gecko 1.9.2): comm-1.9.2/mozilla-1.9.2
(no nightly builds are available any more for these versions, no more updates)
- Intermediate 3.2.x branch (abandoned): comm-1.9.2/mozilla-1.9.2
(this branch was planned but has never been set up, thus no nightly builds are available)
- Released 5.0 version (Miramar, was 3.3; Gecko 5.0): comm-miramar/mozilla-miramar
(no nightly builds are available any more for this version, no more updates)
The update channels for all legacy builds is nightly, thus you will receive daily partial updates if you enabled automatic updates.
Lightning legacy versions:
- For builds from the 1.9.1 branch (TB 3.0.x):
http://releases.mozilla.org/pub/mozilla.org/calendar/lightning/releases/1.0b1/
- For builds from the 1.9.2 branch (TB 3.1.x):
http://releases.mozilla.org/pub/mozilla.org/calendar/lightning/releases/1.0b2/
- For nightly builds from Miramar (TB 3.3/5.0)
(no nightly builds are available any more for this version, no more updates)