How to setup Calendar Sharing between Office 365 tenants

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Sharing calendar information between two Office 365 tenants provides easy scheduling, better collaboration, enhances communication, and contributes to more effective relationship between organizations.

Configuration of Calendar sharing between two office 365 / Exchange online tenants is done by adding Organization relationship in Exchange Online.

You can setup Organization relationship from one Microsoft 365 / Office 365 tenant with another External Microsoft 365 / Office 365 tenant or with an Hybrid / On-premises Exchange organization.

Organization relationship is a one to one relationship between tenants to allow calendar sharing and provide users the ability to view Calendar information of users in External organization.

Its upto the tenant admin on how much Calendar information to share with another organization. For example: Organizations can choose from below options when it comes to Calendar sharing:

  • No access.
  • Access to availability (free/busy) time only.
  • Access to free/busy, including time, subject, and location.

For Example: When setting up organization relationship between two tenants e.g. cloudinfra.net and techpress.net. The configuration of organization relationship needs to be completed on both sides. Let’s see how to configure this relationship to share Calendar information.

Setup Organization relationship between two tenants

For setting up organization relationship, you must have right permissions. Exchange administrators or Global administrators rights are required to create this relationship.

You can create organization relationship either using Exchange online admin center or by using Powershell. We will see both the ways in next sections and create the relationship between cloudinfra.net and techpress.net.

As we know that this relationship needs to be configured on both sides of the tenants. Below is the summary of steps we are going to perform in the next sections of this post:

  • First step is to login on Exchange admin center of techpress.net (first tenant) and add organization relationship.
  • Second steps is to login on Exchange admin center of cloudinfra.net (second tenant) and add organization relationship.
  • Testing to confirm if users can see Calendar free/busy information of external tenant users.

Create Organization relationship in Techpress.net (First tenant)

  • Go to Exchange Online admin center.
  • Click on Organization > Sharing.
  • Under Organization sharing tab. Click on + Add organization relationship.
  • Provide Relationship Name: Techpress-Cloudinfra Calendar sharing
  • Domain to share with: cloudinfra.net

Now on the Sharing options page, Enable Calendar free/busy information sharing and choose the level of information you want to share from your organization with cloudinfra.net.

Sharing options

  • Calendar free/busy information with time only: Selecting this option will provide info of When a user is free or busy.
  • Calendar free/busy information with time, subnect and location: Selecting this option will share a bit more information about a user’s calendar. It will also include Subject of the meeting and Location of the meeting details as well.
  • Everyone in your ogranization: If you want to apply this policy to all Exchange Online users in your tenant then choose this option.
  • A specified security group: You can also create an Azure AD security group and add selected users into the group. You can then specify the group here to target the policy only to those users.

Review the organization relationship and click on Create. Once its in place, you will be able to find it in Organization sharing tab on Exchange Online admin center.

Click on the relationship to find more details about it. Click on Manage general settings.

On Manage general settings page. You will find the details about Application URI and Autodiscover endpoint. Also the list of domains added to organization relationship. You will notice that 73dvgy.onmicrosoft.com domain is automatically discovered and added to the list.

  • Name: Techpress-Cloudinfra Calendar sharing
  • Application URI: outlook.com
  • Autodiscover endpoint: https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc/WSSecurity
  • Domain name: Name of the domains you are sharing Calendar Information with.

Create Organization relationship in cloudinfra.net (Second tenant)

We need to follow same steps on cloudinfra.net tenant as well and add organization relationship with techpress.net domain.

  • Go to Exchange Online admin center.
  • Click on Organization > Sharing.
  • Under Organization sharing tab. Click on + Add organization relationship.
  • Provide Relationship Name: Techpress-Cloudinfra Calendar sharing
  • Domain to share with: techpress.net

All the remaining steps are same as followed previously when we created Organization relationship in techpress.net tenant. Please follow the same steps and create this relationship in second tenant as well.

Add Organization relationship using Powershell

You can also add new organization relationship in Exchange Online using Powershell as well. Please find below steps for the same:

1. Install Exchange Online Powershell module

Install-Module ExchangeOnlineManagement

2. Connect to Exchange Online

Connect-ExchangeOnline

3. New-OrganizationRelationship

New-OrganizationRelationship -Name "Techpress-Cloudinfra Calendar sharing" -DomainNames "cloudinfra.net" -FreeBusyAccessEnabled $true -FreeBusyAccessLevel AvailabilityOnly -TargetApplicationUri outlook.com -TargetAutodiscoverEpr https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc/WSSecurity

4. Get-OrganizationRelationship | Fl

Get-OrganizationRelationship | Fl

End user Experience

Users can open their outlook calendar and add users from another organization to check their free/busy information. This will really help the user while scheduling meeting with partner organization users. Let’s check the results of the organization relationship.

Opened Outlook Calendar of Adelev@cloudinfra.net user and using Scheduling Assistant tried to check if gradyA@techpress.net is available before scheduling a meeting. As you can see that when gradyA@techpress.net is added under Required Attendee, it shows that user is busy from 11:00-11:30 and 13:30-14:00 and rest of the calendar looks to be free.

FAQs

No Information – No free/busy information could be retrieved

If you have recently created Organization relationship in both the tenants and testing it straight away, then you may not be able to see calendar information of the external office 365 user just yet. You may get below message displayed when you try to check the calendar information of external user.

  • No Information – No free/busy information could be retrieved.
  • The external recipient’s server could not be determined. Contact your administrator

Below screenshot shows the error when trying to check the calendar of an external user immediately after configuring Organization relationship. I have waited for around 24 hours and then checked again, I was able to see the calendar information of an external user successfully.

Calendar Free/busy info available from first tenant but not from Second tenant

After configuration of organization relationship, you may notice that from first tenant you are able to see calendar free/busy information of second tenant but not the other way around. This is one of the issues I have faced recently and fixed it using below steps:

If you are trying to configure organization relationship between One Office 365 tenant and another Organization is hybrid / have On-premise Exchange server enviornment.

In that case, you will have to make sure to add mail.onmicrosoft.com domain address of On-premise Exchange server in second tenant’s organization relationship which is fully cloud Office 365 / Exchange enviornment.

  • Make sure to add xxx.mail.onmicrosoft.com domain address in the list of domains.
  • Application URI: outlook.com
  • Autodiscover endpoint: https://autodiscover-s.outlook.com/autodiscover/autodiscover.svc/WSSecurity

Conclusion

In this blog post, we have seen how to setup calendar sharing between two office 365 tenants. We have also see different issues which you may face after configuration of the organization relationship.

If you have One office 365 tenant and another one is hybrid exchange server environmnet. Make sure to add mail.onmicrosoft.com domain of on-prem exchange server in the second tenant. Otherwise, users will not be able to see free/busy calendar information of users who are existing on Hybrid / On-prem exchange servers environment.

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