I'm trying to help a user access a Microsoft 365 work or school mailbox through the Gmail app on an iPhone. Selecting the Office 365 account type takes us to an IMAP setup screen instead of Microsoft's OAuth sign-in page. Entering the Microsoft 365 address and password produces a "User name or password incorrect" error, even though the account works in Outlook and other modern-authentication clients. Does Gmail for iOS support OAuth or modern authentication for Microsoft 365 accounts, or is its Office 365 option still using an authentication method that Exchange Online no longer accepts? I know Outlook for iOS and Apple Mail are better-supported options, but I'd like to know whether Gmail can work for this particular user.
3 Answers
Microsoft 365 has moved away from basic authentication, and entering the normal mailbox password into an IMAP form won’t satisfy modern authentication or MFA requirements. The Gmail app would need to launch an OAuth login for the account, and in this case it isn’t doing that. I’d stop troubleshooting the password and use Outlook together with Microsoft Authenticator or another approved authentication method.
This is a client compatibility issue rather than a bad password. Gmail’s Microsoft account setup doesn’t appear to support the current Exchange authentication method, while Outlook uses Microsoft’s supported protocol and sign-in process. For a managed work mailbox, Outlook for iOS is the practical answer; Apple Mail may also work if the organization allows it.
The Gmail app on iOS generally doesn’t support the Microsoft 365 authentication flow required for work and school accounts, especially when MFA or newer Exchange Online requirements are involved. The Office 365 option falling back to IMAP instead of opening Microsoft’s sign-in page is the main clue. An app password might work only in limited legacy configurations, but it usually isn’t a dependable solution for Exchange Online.
I’ve seen the same behavior on Android as well. Even when the setup screen accepts the account details, it either fails with an authentication error or hangs during sign-in, so switching to Outlook is usually the only reliable fix.