Create Calendar Single-Value Property

You can add custom metadata to an Outlook calendar by creating a single-value extended MAPI property, which requires the calendar's unique identifier, a property ID, and a string value to store custom data like project codes.

An extended MAPI property in Microsoft Outlook is a custom data field that allows you to store unique string metadata not covered by standard calendar fields, using a specific property ID and value.

You need to create single-value extended properties on a calendar when you want to associate custom string metadata, such as a specific client identifier or project code, directly with the calendar for easier filtering and reporting.

Yes, you need an authorization token to store custom data on an Outlook calendar. The operation also requires a specific content type in the request body, which includes the MAPI property ID and its string value.

You define a custom MAPI property ID for an Outlook calendar by providing a specific formatted string in the request body, such as 'String {guid} Name Color', along with the associated string value you want to store.