>>Whatever Gmail wants is essentially a defacto standard. Gmail have solved it with a Oauth authorization scheme. Basically, first time setting up mail, you are asked to authenticate by 2FA in a webview, then a shared secret is established, that is used during SMTP and IMAP time. Both Hotmail and Gmail is using this hackish webview solution for Outlook integration (and integration in some other email clients).
Thats why Google and Microsoft have their own buttons inside Outlook and some other mail clients.
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