Today we’re rolling out an improved UX for macOS/iOS & Android users! 
Under the My Account → Domains → Aliases → Generate Password pop-up, you can now easily scan a QR code which will open a signed mobile config (provisioning profile) at the generate password page for your IMAP/POP3/CalDAV mailboxes/aliases.
This means you don’t need to enter a password nor host/port configuration, and saves you a lot of typing (albeit K-9 mail still requires you to enter a password, but we provide 1-click copy-to-clipboard buttons).
Screenshot:
