Mozilla Messaging competed the merge for Thunderbird 13 Beta on April 26th and Thunderbird 14 Earlybird on April 27th. Existing Earlybird and Beta users can update (within the same build) to the newest version by going to Help > About Thunderbird (or Earlybird). Users wanting to move from the Earlybird to Beta, Beta to Earlybird or do not currently have a version of Thunderbird Earlybird or Beta installed will need to manually update via The Future of Thunderbird site.
Planned Release Dates (subject to change):
- Thunderbird 13: June 5th, 2012
- Thunderbird 14: July 17th, 2012