What is a tenancy?

A tenancy in Office 365 refers to the full Office 365 suite attached to a domain. When Office 365 is set up, it creates a tenancy to store all the data for Office 365 including things like SharePoint, OneDrive and Yammer. This allows all of your organisations data to sit in the same environment and be moved around within the tenant with ease.

The second part of the tenant is the data that feeds into it. Exchange data and Active Directory data are fed directly into your tenant. But what does that actually mean?

  • Exchange is the name of the email service. All the exchange data relates to email and in this scenario can be thought of as the foundation for email.
  • Active Directory is the name of Microsofts domain management system. In this scenario, it helps all the apps talk to each other within the same tenant.

Merging tenancies

Tenancies can be merged in the case where both tenants wish to create a more seamless flow of data between the two organisations. When a tenancy is merged, you essentially move the tenant inside another and recreate the Exchange Data and Active Directory Data.

An important thing to note is that when tenancies are merged, the existing mailboxes will be destroyed and setup on the new Exchange service.


At Schools ICT, we can assist you in merging tenancies to create the best transition between mailboxes. Our pricing is as followed

  • £111 for two hours work to move the existing tenancy
  • £40 for every mailbox that will be kept the same


  • Even though we are picking up an existing tenancy and moving it, the users will receive a new inbox when the tenancy is moved. To prevent the entire mailbox being deleted, we can back up mailboxes and restore them in the new tenancy however, backing up the mailbox is where the additional £40 per mailbox comes in and we recommend backing up as few mailboxes as possible
  • The £40 mailbox charge is assuming the mailbox has been cleaned up following our cleanup guide


The diagram below shows the basic setup for an Office 365 tenant.

tennancy diagram large flat

Every tennant has Exchange Data and Active Directory Data that connects your all your email and login information. This means in the above example, Company A has their own exchange data (email) and their own login information (active directory) which hooks into their tennant.

Now we can introduce Company B who also have their own Office 365 Tennant with their own exchange and active directory data.

tennancy diagram two tennants flat

Now we have two seperate companies that access seperate data and also send emails from different email addresses. If these two companies decided to merge so they could share the same data they would need to merge tenancies.

tennancy diagram merged flat

Now the companies can access the same data however, they retain their own identities.