What's an Office 365 user ID and why do users need one?

Applies to Dynamics 365 (online), version 9.x

Each user signs in to Dynamics 365 (online) with an Office 365 user ID (more precisely, an Azure Active Directory user ID, see the Note later in this topic). Access to Dynamics 365 (online) is controlled through the Office 365 user ID.

The user ID is in this format: username@yourcompany.onmicrosoft.com. Please note that although it resembles an email address, this is a sign-in ID and not an email address. It can be used as an email address, but only if you have an Office 365 subscription with Exchange Online.

Many companies would like to use their own domain name, such as contoso.com, instead of onmicrosoft.com for user accounts. You can configure Office 365 to use your domain name so your Dynamics 365 users can sign in with a format like username@yourcompany.com instead of username@yourcompany.onmicrosoft.com. More information: Verify your domain in Office 365

To manage Office 365 user IDs, sign in to the Office 365 Admin Center (https://portal.office.com). Here, you can do all sorts of administrative tasks such as create users, assign licenses, and maintain passwords.

Office 365 user ID and Dynamics 365 (online)

Note

Dynamics 365 (online) uses Azure Active Directory as its identity provider. You access Dynamics 365 (online) through an Azure Active Directory user ID that’s created and managed in the Office 365 Admin Center. For simplicity, we will refer to the Azure Active Directory user ID as the Office 365 user ID in this documentation.

If you company uses on-premises Active Directory for user identity, you have options that can simplify user management such as providing a single sign-on experience for your users. More information: Manage user account synchronization

See also

What is my user ID and why do I need it for Office 365?
Use the Office 365 admin center to manage your Dynamics 365 (online) subscription
Create users and assign security roles