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How Does Free/Busy Works between two different office 365 Tenants and Configure

Updated: Dec 29, 2023

Hello Windowstechpro Viewers, Welcome Back!!

In this Article, We are going to see How Free/Busy Sharing Works in the federation Trust enabled two different Office 365 Tenants and How to Create Organization Relationships to share Free/Busy Information.

How does Free/Busy Sharing Works?


Consider Tenant 1: User wants to see the free/busy information of the Consider Org relationship already created for now( Will show you how to rater in this article).

Below is processes followed in this free/busy information retrieval,

Step 1: trying to retrieve the free/busy information of the, hence it contacts the Exchange Online.

Step 2: Exchange Online does organizational relationships lookup and verify the domain whether it is already added.

Step 3: Once Organizational Relationship verifid, Exchange online Contacts the MFG(Microsoft Federation Gateway) and requests for the Auth token for Southtunes,in.

Step 4: MFG provides the Auth token along with Autodiscover endpoints of the domain to contact since is already has A Trust Relationship with MFG.

Step 5: Exchange online does the Autodiscover request Web request to the domain to retrieve the free/busy information of the user

Step 6:'s Exchange Online will check the token received from the MFG and the Free/Busy Request.

Step 7:'s Exchange Online verify whether Org Relationship for already created

Step 8: Once verification completed, Exchange online of gets the Free/Busy information of the user

Step 9: information sent back to the Successfully.

That is it.. The process is simple and Secured.

Now Let's see how to create the Organization Relationships between the Organizations to share the Free/Busy Information between them.

Process 1:

Tenant 1: Configuring the Organization Sharing Policy

Login to the using the Administrator Account

Go to Organization --> Sharing and click on (+) to create new organization sharing


Enter the Relationship name , Domains to share with and check the Enable Calendar free/busy information sharing and enable the any one of the option based on the requirement.

Note: You can enable sharing the complete Organization or specific group of people


Once you click on save new Sharing policy gets created and also it retrieves all the SMTP Domains associated with Tenant.


Process 2:

Tenant 2 : Configuring the Organization Sharing Policy

Login to the using the Administrator Account

Go to Organization --> Sharing and click on (+) to create new organization sharing and follow the same steps as process 1.




Process 3: Testing the Free/Busy Information

Login to the OWA or Outlook Application, Click on Calendar- New Scheduling Assistant


Enter the Email address of the another tenant user,


You can see now free/busy information has been retrieved and shown availability of the User.


Great!!. It is very simple to configure and use between two different Office 365 tenants.

Some Recommendations to configure the Sharing Policy,

  1. It is better to have separate organization Policy for Each domain if your organization has different sharing options.

  2. If the Sharing Options are common, keep single Organization Sharing Policy and keep adding the domains whenever you need to enable the sharing. hence that multiple lookups can been avoided and users will get immediate response. in turn, you will reduce the time taken for the retrieval.

  3. Before configuring the Sharing policy, refer the Microsoft Article for more details about the Limitations.

  4. If you're enabling in Hybrid environment, Refer the Article for the Firewall requirements of the on-premises Exchange Servers / End Points

  5. Federation plays important role in the free/busy sharing, it is better to know more about Federation

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