"Thunderbird 3.0 is the first major release of Thunderbird in
years and that's a very bad thing in my view. Unlike its cousin
Firefox which has had regular releases and enjoys a large user-base
and following, Thunderbird (to date) hasn't generated the same type
of attraction.
"Back in 2007, Mozilla tried to kick start Thunderbird
development by spinning out a new organization called Mozilla
Messaging which was tasked with building Thunderbird. What have
they done in the last two years?".