According to a recent change, Thunderbird is now the default email client in Ubuntu 11.10 Oneiric Ocelot, replacing Evolution. The update should be available for Oneiric users in a few hours.
But this doesn't mean Thunderbird will be default in the final Ubuntu 11.10 Oneiric Ocelot release because according to the default email client blueprint, the final decision has not been taken yet. We should find out if Thunderbird will stay as default sometime around Ubuntu 11.10 Oneiric Ocelot Alpha 3, after both Thunderbird and Evolution will be evaluated:
Work items for oneiric-alpha-3:
[charlinepoirier] Usability testing, compare Thunderbird and Evolution: TODO
[mconley] Deliver launcher integration: TODO
[chrisccoulson] Deliver messaging menu integration: DONE
[chrisccoulson] Merge indicator-appmenu integration upstream: TODO
[mconley] Final work on contacts integration, ability to read/add/edit contacts in existing address book: TODO
[chrisccoulson] Deliver calendar events in the datetime menu: TODO
[jasoncwarner] Final evaluation, will Thunderbird be default email client: TODO
Back at the Ubuntu Developer Summit in Budapest, it was decided to stick with Evolution but switch to Thunderbird if it integrates with the Desktop and if there's enough space on the CD.
And the latest Thunderbird 5 in Oneiric does look like a great improvement: the theme finally integrates well with the default Ubuntu theme, Thunderbird now uses NotifyOSD notifications and it will make use of the Messaging Menu by default (the extension that makes Thunderbird integrate with the Messaging Menu still needs some work - at least for me it's not working properly yet). And of course, it also comes with Unity quicklists:
But there are still issues that need to be addressed, such as Ubuntu One integration (contacts) or calendar integration. Work for this is already in progress so it seems Thunderbird will be ready in time for the evaluation. We'll let you know when a final decision regarding the default email client has been made.
Even if Thunderbird won't be the default email client after all, it's still great to see it so well integrated with Ubuntu / Unity, especially since the majority prefers Thunderbird over Evolution.