(Also using Airmail here, for a few weeks now.) By default, Cmd-Delete will delete the message, Delete will archive. There is a "Use Delete Key (backspace) for

(Also using Airmail here, for a few weeks now.) By default, Cmd-Delete will delete the message, Delete will archive. There is a "Use Delete Key (backspace) for Move to Trash" configuration option as well, in the General config pane.