When building your web application or Windows Store app accessing Office 365 data, you might be working with just your Office 365 tenant. However, when you publish your app, you may want to make your application available to all Office 365 users (depending on your scenarios). This means, users not only from your Office 365 tenant, but also from other tenants will be able to log in and use your application.
Publishing your Office 365 App
In the Office 365 API tooling, you will notice there is an option for App Properties
App Properties, as its name suggests, is where you can edit some of the properties available for your Office 365 app.
Today, you can edit the following:
– Name of your application
– Multi-tenant configuration
Making your App Available to Multiple Organizations
If you want your application that is consuming Office 365 data using the Office 365 APIs to be accessed not only by your organization but also from other external organizations, then you will need to set this setting to Multiple Organizations.
Setting this to Single Organization will only allow your single-organization users to access the Office 365 data.
NOTE: An Office 365 app is nothing but an Azure Active Directory application and thus this setting applies to the Azure Active Directory Application. Hence, this will be applicable to any other (non Office 365) resources that your app is consuming.
Another thing to note is that this setting is only available to web applications and not for native client applications such as Windows Store apps. For native client applications, this is set to Multiple by default.
I would highly recommend reading the documentation before you publish your application to make the right decision.
How does this work?
You have now configured your app to be available to multiple organizations and you may ask what happens when external users sign in.
When external users sign in, they will see the consent dialog and have to grant access to the application to access their Office 365 data.
With the Office 365 API tool, you can easily configure for your application consuming Office 365 API to be available to not only your organization but also to external users who may belong to multiple organizations.