List of authors in git since a given commit

I want a way to list all git authors that

1. Is only since a given commit.
2. Is unique.

These two are easy, and I've seen some solutions to this online, most using git log --format. But none that I saw fits the additional requirements:

1. Is ordered by commit date. So if John Smith committed before Aaron Meurer, his name should appear before mine (I'm Aaron Meurer).
2. Respects .mailmap. As far as I can tell, only git shortlog does this, and it gives a bunch of extra stuff that I don't want. But maybe I'm wrong. Or maybe those of you who are more handy with sed and friends than I am would just use that.

(by the way, how do I make Markdown not restart the numbering?)

I also want a way to order it by last name, but this is relatively easy.