Checkout Thunderbird 3 repository

Build document in wiki.mozilla.org is too old. I explain enlistment of Thunderbird 3.

checkout comm-central repository

Thuderbird 3 / Seamonkey 2 repository is moved from cvs.mozilla.org to hg.mozilla.org.

$ hg clone http://hg.mozilla.org/comm-central/

checkout other project

Thunderbird 3 depends on mozilla-central and other project such as LDAP C-SDK. So you need checkout other projects

$ cd comm-central
$ python client.py checkout

Good luck!