Using more than one domain inside of an Office Add-In

In this article I am going to introduce the  <AppDomains> parameter within an Office Add-In Manifest. Using this parameter we are going to see how you can change the URL within an Add-In and consider the possibilities that brings us.


I was casually reading through the thrilling “Office Add-ins XML Manifest” ( and I came across this casual comment:

By default, if your add-in tries to go to a URL in a domain other than the domain that hosts the start page (as specified in the SourceLocation element of the manifest file), that URL will open in a new browser window outside the add-in pane of the Office host application. This default behavior protects the user against unexpected page navigation within the add-in pane from embedded iframe elements.

To override this behavior, specify each domain you want to open in the add-in window in the list of domains specified in the AppDomainselement of the manifest file. If the add-in tries to go to a URL in a domain that isn’t in the list, that URL will open in a new browser window (outside the add-in pane).”

This was the exact problem I had when I came up with the O365Token solution on how to Authenticate an Add-in to O365 and ended up using a solution. When I tried to do the OAuth redirect it failed because it opened a whole new Internet Explorer instance which did not communicate with the Add-in parent.

The published solution works but is a somewhat poor user experience due to the Internet Explorer window opening up. But hey it worked so I went with it.

The problem demonstrated
I am demonstrating this issue using firebuglite in one of my existing Add-ins. I change the location.href of the Add-in (in Outlook) and the requested website opens up in a fresh Internet Explorer window.



Proof of concept

I created a simple addition to my manifest file:


I uploaded the new file through the Exchange admin portal, refreshed it for the user and tested it again



and look at that – it opened within the Add-in without issue.


In this article I have demonstrated how using the  <AppDomains> parameter within the manifest file we are able to change the website loaded within the Add-in

Next – how do we re-write the O365Token to load nicely in this window?


3 thoughts on “Using more than one domain inside of an Office Add-In

    • I can’t imagine why the manifest would be dynamic – the only thing I could suggest is that you use one site as a proxy for all the others. I am interested to see what the microsoft boys say though, they should be watching as you tagged it correctly.

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