This is really a very useful and great addon.
But one option is missing.
It happens all the time to me, when replying to a message stored in archive folder, that I use an unwanted Identity
So it would be great if it was also possible to choose in the Options for "none" / "empty" or alike as choice for "When Composing a new message"
That way, while composing the mail, selecting an identity manually becomes mandatory.