I've just heard from Apple that they will enforce two-factor authentication from June 15, and all non-Apple apps that use iCloud must have an app-specific password.
Last time I tried two-factor authentication I had problems connecting with Aquamail and reverted to single-factor.
I know how to set up an app-specific password, but before I set it up, I'd just like to check that Aquamail is set up for it. I presume it is, but just checking.