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Mailbox.getCallbackTokenAsync method (JavaScript API for Office)

Office Add-ins

Gets a string that contains a token used to get an attachment or item from an Exchange Server.

Last modified: July 06, 2015

Note Note

The name "apps for Office" is changing to "Office Add-ins". During the transition, the documentation and the UI of some Office host applications and Visual Studio tools might still use the term "apps for Office". For details, see New name for apps for Office and SharePoint.


App type: Mail

Available in requirement sets


Last changed in Mailbox


Applicable Outlook modes


See all support details

Office.context.mailbox.getCallbackTokenAsync(callback, userContext);


The method to call when the asynchronous load operation is complete. Required.


Any state data that is passed to the asynchronous method. Optional.

The getCallbackTokenAsync method makes an asynchronous call to get an opaque token from the Exchange Server that hosts the user's mailbox. When the server responds, the method specified by the callback parameter is called with one parameter, the result object. The result object has the following two properties:

  • Context — Contains the data in the userContext parameter.

  • Value — Contains the token.

You can pass the token and an attachment identifier or item identifier to a third-party system. The third-party system uses the token as a bearer authorization token to call the Exchange Web Services (EWS) GetAttachment or GetItem operation to return an attachment or item.

Your app must have the ReadItem permission specified in its manifest to call the getCallbackTokenAsync method.

The lifetime of the callback token is 5 minutes.

In this article, "Outlook" refers to Outlook for Windows, Outlook for Mac, Outlook RT, OWA for Devices (OWA for Android phones, OWA for iPad, OWA for iPhone), and Outlook Web App. "Outlook rich clients" refers to Outlook for Windows, Outlook for Mac and Outlook RT. At this point, Outlook for Mac supports JavaScript API for Office in only Outlook read mode, and can activate mail apps that reference office.js version 1.0 or 1.1 and use apps for Office schema version 1.0.

A checkmark (√) in the following table indicates that this property is supported in the corresponding Outlook host application. An empty cell indicates that the Outlook host application doesn't support this property.

For more information about Office host application and server requirements, see Requirements for running apps for Office.

Supported hosts, by platform

Office for Windows desktop

Office Online
(in browser)

OWA for Devices

Office for Mac


√ (Read mode only)

Available in requirement sets


Minimum permission level


App types










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