Lightning on SeaMonkey: News from the front

Hi everyone,
two days Robert Kaiser (KaiRo) checked in a fix for bug 313822, thereby enabling Lightning as an extension for SeaMonkey.

As this has been a long-standing request from SeaMonkey users (since we officially retired the Calendar extension over 20 months ago), I want to address some questions and issues up-front:

Which versions of Seamonkey does Lightning support?

Lightning support is only available for current trunk builds of SeaMonkey (code-named Suiterunner). These builds will one day become SeaMonkey 2.0.

Why are the current Seamonkey 1.1.x releases and the old 1.0.x releases not supported?

Both the 1.1.x and the 1.0.x releases are based on older code (XPFE) which is technically incompatible with Lightning. Therefore Lightning will not be available for those releases.

Will future releases of Lightning be made available for SeaMonkey as well?

No. Lightning support for SeaMonkey is currently experimental and there are known issues, which need to be resolved first. In addition, only Lightning builds from the trunk will work with SeaMonkey, but the developer focus is currently on the Mozilla 1.8 branch, as this is the code that the current Thunderbird release is based on. Lightning developer focus will only switch to what is now the trunk, once Thunderbird 3 is released. We expect the Thunderbird 3 release within the next 12-24 months.

Does this mean that SeaMonkey will only be a 2nd-class-citizen?

Yes, that is true. As the Lightning developers do not currently focus their efforts on the trunk and as no Lightning developers use SeaMonkey as their mail client, SeaMonkey will remain a 2nd-class-citizen until both of these facts change.

Does this mean that I shouldn’t file any bugs?

No. Please file bugs as you find them (but please search for duplicates first). However, all bugs filed by SeaMonkey users must be cross-checked with either Sunbird or Lightning on Thunderbird first, to identify whether a bug applies to Sunbird or Lightning on Thunderbird (or both) as well.

What happens if a SeaMonkey user does not cross-check a bug with Sunbird or Lightning on Thunderbird first?

All bugs, which have not been cross-checked with Sunbird or Lightning on Thunderbird will be resolved as INCOMPLETE immediately. They will only be reopened, once the cross-check with Sunbird or Lightning on Thunderbird has been performed.

What about bugs that apply only to Lightning on SeaMonkey?

A new component named “Lightning: SeaMonkey Integration” has been created for bugs, that relate only to the integration of Lightning into SeaMonkey. The policy described above does not apply to bugs filed in this component.


  1. You referred to Thunderbird 3.0 being released in the next 12-24 months.
    With the recent discussion on the possible end of Thunderbird at Mozilla (sad sad day if it comes to that), will we ever really see a Thunderbird 3.0?
    What are the implications for ongoing Lightning development?
    We were getting closer and closer to a true Outlook replacement.
    Is this all derailed now?

  2. We currently have no indication that Thunderbird development will come to a stop. Therefore we still expect a 3.0 release of Thunderbird.

  3. SeaMonkey and Lightning Calendar

  4. Ridiculous!
    Seamonkey is living, but maybe Thunderbird 3 never will live.