You have got to add support for App Passwords for Office 365 email accounts in the Outlook for Mac. It is crazy that someone would have to type in a 6 digit code every time they go to check their email if their work has enabled multifactor authentication on their Office 365 user account. App passwords work for the Windows Outlook desktop application and the native email application on most smart phones. Why would Microsoft' email app (i.e. Outlook for Mac), not support this?
John Welch commented
In the account creation dialogs, if it's a .Mac/iCloud account, include text about one-time passwords for two-factor auth, and a link to the Apple account management site. This would remove significant friction.