How to Obtain a Unique Identifier for a Mailbox in Microsoft 365 Using Graph API

Question

What is the stable and unique identifier for a mailbox in Microsoft 365 that can be retrieved using the Microsoft Graph API or Office.context? Which property should be used to ensure consistency across different API calls?

Answer 1

Hi Diksha Yadav,

Thank you for reaching out to Microsoft!

The stable and unique identifier for a mailbox in Microsoft 365 is the "id" property, which is a GUID (globally unique identifier). This identifier remains constant for the lifetime of the mailbox.

To obtain immutable identifiers for Outlook resources, you can retrieve the ID using the following request: Obtain immutable identifiers for Outlook resources

GET https://graph.microsoft.com/v1.0/Users/{userprincipalname}

The JSON response will include the "id" value.

Hope this helps.

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