Comment 15 for bug 630281

Created attachment 474767
Set the default mail handler to MOZ_APP_LAUNCHER if it is set

Here is an updated patch which uses MOZ_APP_LAUNCHER if it is set. If it isn't set, then it falls back to the current behaviour.

I've tested this and it seems to behave correctly with all combinations of relative/absolute path and with/without the launcher in the users $PATH.