Guest user login method

Hello @Satoshi Suzuki,

Thank you for posting your query on Microsoft Q&A.

Based on your description, I understand that you are trying to add external users as guest users in your Entra ID and wish to use mail OTP as a login method for all guest users. This is not possible because Microsoft Entra ID automatically signs in the user based on the user's identity provider. Please refer to the following documentation that explains how the redemption flow works based on the user profile (i.e., MSA/Entra ID):

https://video2.skills-academy.com/en-us/entra/external-id/redemption-experience#redemption-process-limitation-with-conflicting-contact-object

For example:

1. If the invited guest user is part of Entra ID, the sign-in process will be initiated to the user's home directory.
2. If the invited guest user is part of a Personal Microsoft Account (MSA), the redemption process will be initiated to the MSA identity provider at the time of sign-in.
3. If no home directory is found and the email one-time passcode feature is enabled for guests, a passcode is sent to the user through the invited email. The user retrieves and enters this passcode in the Microsoft Entra sign-in page.

I hope this information is helpful. Please feel free to reach out if you have any further questions.

Please Accept the answer if the information helped you. This will help us and others in the community as well.

Thanks,
Raja Pothuraju.