Email one-time passcode (OTP) — Enable guest users without federation or registration

Nowadays, if you use Azure to run your business, there is an 80% chance of using Azure AD as the Identity and Access Management system. The strong integration with on-premises AD tenants, Google, Facebook and Azure AD B2B and Azure AD B2C makes our life much easier.

What if you provide access to an external user that cannot be authenticated using AD, MSA (Microsoft Account) or social identity providers? Or you don’t know what kind of IAM the user has.

OTP (Email one-time passcode) is your friend in this situation. The feature enables us to share resources or provide access to external users without requesting them to create an account. The only thing that the user needs is an email address and nothing more.

The one-time passcode is sent to their email address at the moment in time when they want to access the resource that you shared with them. The passcode is valid for 30 minutes and provides a valid session for the next 24 hours. If the passcode or session expires, there is no problem because the external user can request a new passcode again.

It’s a great way to share resources with external users, especially when there is no federation or integration with their IAM system. The external user is added as guest to your Azure AD, and they are subject to Azure AD access policies (e.g. MFA) and can be managed directly by you.

When OTP is active, there is a small trick. When you share a resource with an external user, you don’t know if OTP will be used or not. The OTP is used if the user:

• Don’t have an MSA (Microsoft) account
• Don’t have an Azure AD account
• No federation configured with their tenant

Because of this, when a user already used OTP and later gets an MSA, Azure AD or Ferederated account, they will still use OTP. From Azure AD, you will need to reset their redemption status to allow them to use another method.

The excellent integration with OneDrive and SharePoint enables us to use OTP to share content with Guest users. Why? Because OneDrive and SharePoint are using Azure AD, the OTP is fully integrated (as long as your IT allows OTP (big smile).

Why you should use OPT (Email one-time passcode)?

A simple way to share content and provide access to your organization to external users that are not part of your tenant or a federated tenant. The access control it is fully managed by your organization and audited. Who, what and when can access is fully managed by IAM, as you would managed a guest user.

Because of this, OTP can be used with success to share notes and materials after a meeting with external attendees.