[Naac]

Does clicking on "New Message" still create a new window instead of letting the new message be composed in a tab?

That's the one "feature" I've been waiting on that just seems to be stuck in limbo.

Looks like the bug is still open: https://bugzilla.mozilla.org/show_bug.cgi?id=449299

[autoexec]

ideally you'd be able to do either. I much prefer new windows when opening existing messages or writing new ones, but I wouldn't assume that works best for everyone else