Thunderbird Conversations is a new extension from the Mozilla team which brings Gmail-like conversation view to the Thunderbird inbox. Once installed, the open source email client loads entire threads of conversation in the reading panel when clicking an email thread. Just like Gmail’s conversation view, unread messages are expanded and those that are previously read remain collapsed.
Aside from the conversation view, this addon adds inline reply buttons to quickly reply to an email thread. Hovering the mouse over a contact displays their avatars and links to their various social network profiles if you have “Contacts for Thunderbird” installed.
Watch the screencast.
Thunderbird Conversations is compatible only with Thunderbird 3.3 alpha.