Apple Mail has a cool trick with the Reply/Reply All keyboard shortcuts. If I tap Cmd-R to open a reply window and then change my mind, deciding I need to Reply All, all I have to do is tap Cmd-Shift-R, and the open message is populated with all the other recipients. The reverse also works, if I inadvertently Reply All, I can use Cmd-R to switch to just the one sender as recipient. I would love it if Airmail 2 could do the same thing.