monline

If I remember well, the shortcut in my Thunderbird at home (TB 2.x, Mac OS X 10.5.x Leopard) for starting a new message is Cmd+Shift+M. I'm not sure whether this is so by default (at least the official list of TB shortcuts tells me otherwise) or it was me who remapped it to this combo, but the fact is that I use this shortcut for this functionality. However at the office I use Ubuntu and TB has the "Move again ..." functionality assigned to this shortcut by default. Using the Keyconfig extension you can rebind almost all shortcuts of Thunderbird (or virtually any Gecko based app that you can install the extension into). With this extension you can make sure that the shortcuts are the same, whereever you use a specific app.

Btw. I wonder how does the functionality of keyconfig not belong to the core Gecko engine? I think this is just as vital as having the config panes in both Firefox (about:config) and Thunderbird (in Advanced preferences) for low-level config changes.
It's also interesting that this extension has no official homepage and it's not available from addons.mozilla.org either. Ok, it has a "homepage" (sort of), but a raw directory listing is not something I'd really call a homepage for an app.