dhk schrieb am 05.03.2011 22:42:
> Yes, that's the problem.  I guess it means it will be in the next
> version.  In the meantime I added "=mail-client/thunderbird-3.1.7" to
> /etc/portage/package.mask and everything seems to be fine.

Just sync your portage tree and you should be able to install
thunderbird again.

-- 
Daniel Pielmeier