A few weeks after we had initially set up an l10n dashboard for Thunderbird, Calendar and SeaMonkey localization, Axel Hecht (Pike) managed to import the Thunderbird, Calendar and SeaMonkey trees into the main l10n dashboard as well.
We have let these two dashboards run in parallel for the last few weeks, but in the end, it didn't make any sense to have two dashboards for the same thing. We have therefore retired the Mozilla Messaging l10n dashboard and redirected all calls to it to the mozilla.org l10n dashboard. Please use the mozilla.org dashboard exclusively from now on.
To make you more familiar with the various options, that the dashboard provides, I've written up a short guide to its various functions on the mozilla.org wiki. I'd appreciate feedback on this guide.