>>> Emerging (1 of 125) mail-client/mozilla-thunderbird-1.5.0.8 to / (...) [ ok ] * checking ebuild checksums ;-) ... [ !! ] !!! Digest verification failed: !!! /usr/portage/mail-client/mozilla-thunderbird/mozilla-thunderbird-1.5.0.9.ebuild !!! Reason: Filesize does not match recorded size !!! Got: 7822 !!! Expected: 7823
Fixed; emerge --sync and you should be good.