Microsoft Office 365 Rebranding 101: Email Address Changes

Rebranding Microsoft Office 365 email addresses is often the final and most visible milestone in an Microsoft Office 365 tenant to tenant migration (See Office 365 Tenant to Tenant Migration Series –  The Challenge Defined). You’ve successfully executed the project plan, informed your users, migrated the data, and even modified your MX records. Both organizations are now officially under one roof. So how do we take that final leap and rebrand your users?

First, we’ll need to identify where we’ll be performing the work. The location the work is performed in depends on your identity management solution and your source of truth. There are many providers: Windows Active Directory, FS, Okta, Azure AD Connect.

For example, a Microsoft Office 365 tenant using Azure AD Connect has the on-premises Windows Active Directory as the source of truth. As a result, you will work within Microsoft Windows Active Directory on-premises to achieve the rebranding.

Now that we know the where, we can discuss the how to rebranding Microsoft 365

Our first step is to perform a comparison of both organizations naming conventions. Often, merging companies have naming conventions that are out of alignment. Rebranding is an opportunity to fix this misalignment.

The following are examples of misaligned naming conventions:


Company A

Company B

Alice@CompanyA.comBobH@CompanyB.com
AUprush@CompanyA.comBobHeard@CompanyB.com
Alice.Uprush@CompanyA.comBob.H@CompanyB.com

Once we’ve settled on a naming convention, we’ll need to modify the primary SMTP addresses of Company B to match the naming convention of Company A, and replace the domain suffix. We’ll perform this step in Excel, as we can easily check if there are any conflicts in our new addresses. For example, each company may have an Accounting@, Marketing@, Alice@ etc. If there are conflicts, we will either merge the mailboxes, or discuss modifications to the address with the project point of contact.

Once everything checks out, we’re ready to begin the rebranding process! At a predetermined time, usually after business hours, we’ll proceed to that magical source of truth, Windows Active Directory, and execute the rebranding.

Our scripts will iterate through each Windows Active Directory identity, stamping them with their brand-new address, while maintaining previous aliases. Once complete, we’ll kick off an Azure AD Connect initial synchronization, and watch as each user is rebranded within Microsoft Office 365.

MERGERS & ACQUISITIONS:  With our team’s assistance you will accelerate the integration of your information technology assets.  Enclyne specializes in merging messaging systems, document management and server and networks.  Use our experience to ensure your merger’s success.