Changing the Primary Domain for Users Accounts – Office 365

After you add and verify your own domain successfully in Office 365, you can change your primary email address from the default to the domain you just verified. Steps below:

  1. Log in Office 365 Portal and go to the Admin page.
  2. Click Users
  3. Select the user and click Edit.
  4. Click Details
  5. Click the dropdown list of domains beside user name and choose your own domain.
  6. Click Save.

Why is there still the domain after I added and verified my own domain in Office 365? The will not and cannot be deleted from Office 365. This is the primary domain that Microsoft uses in its multitenant environment, also known as Office 365. Just accept that it’s there and don’t worry about it.

Thanks for visiting and reading my posts. I am always looking for more ideas. Please comment or email me with what you would like to see.

Kelsey Epps

Office 365 MVP

Email Me Follow me on Twitter Connect with me on LinkedIN Facebook Me

26 thoughts on “Changing the Primary Domain for Users Accounts – Office 365

  1. Paul

    Hi there. We are thinking or changing our domain name from say to but was wondering if Office 365 could be setup in such a way that if someone emails someone from our company with the OLD domain name it will still get through? Hope this makes sense :)

  2. NMF

    2 questions:
    – If a user has stuff stored on skydrive on the domain and we change it to our domain does it keep the skydrive files?
    – Do you know if there’s a way to setup Outlook on the computers before changing the dns mx record? We have our emails stored on another service and we want to configure the computers of everyone before changing providers, that way we will give our users some time to change the emails from one account to the other or just archive it. We tried setting it up like the usual but it seems that the wizard on Outlook cant reach the office365 server

    1. Kelsey EppsKelsey Epps Post author

      1) Yes. The account is still the same, you are just changing the UPN

      2) Make sure that all your users are licensed for Office. Download and install the new version on to the desktops. Configure a new Outlook profile with the old server and Office 365. You can have multiple mailboxes in one Outlook profile. After you flip the switch make sure that the Office 365 mailbox is the primary on the profile and then have the users move the mail from old to new.

  3. Sumedh Sathaye

    Hello, can one change the domain from to If yes, how? Thanks in advnace

    1. Kelsey EppsKelsey Epps Post author

      At this point there is no way to rename a tenant. Just open a new one with the new tenant name.

      1. Nick

        Do you have steps or a link that might outline how to do this? I figured powershell could do it (Powershell can do anything! Its awesome!), but I’m not sure exactly what needs to be involved (newer powershell user).

  4. Paul

    Hi, if I change the primary email address after adding my domain does that mean that I’ll have to login with my new email address or will my login remain the same?

  5. James

    If I change the default domain for a user will outlook require logging back into the account with the new account details or will it automatically do it for us?

    1. Kelsey EppsKelsey Epps Post author

      Depends on the version of Outlook. Chances are that you will need to at least close Outlook and open again.

  6. Davy Montgomery

    Is this still true that you cannot change the ONMICROSOFT domain? It was not made clear to us when we first signed up what this address would be used for. To make matters worse what we typed was shortened (from 24 characters to 21).

    So we are left with confusing URL’s for our Sharepoint. Microsoft support didn’t even understand my request and refused to allow me to speak to anyone else.

    We are a non-profit so it would be painful to move to a new office 365 space as I’m of impression we would have to get re-approved with non-profit status. Any suggestions or thoughts would be a welcome thing.

      1. steve88

        This response isn’t complete. You can’t change the tenant name (, but you can add your own domain and change the email address so the users use the domain you want.

        No need to look for another provider.

        1. Kelsey EppsKelsey Epps Post author

          The post isn’t about changing the tenant name, you have a to create a new tenant for that. This post is about changing the primary domain for user accounts.

  7. Mark

    We are a small non profit with four separate offices and each runs its own AD. We have a public web site ( and the users at our main office sign in to Exchange etc. using that domain.

    We have validated that domain while establishing our new Office 365 subscription (had our DNS hosting company add a TXT record) but, at the moment, I have kept the as the primary domain in O365.

    Is it possible to make our existing domain in Office 365 the primary and use that domain for setting up users (so they have the same domain for their sign-in to O365), but continue to use all our existing on-premises Exchange, AD etc. That is, not migrate to Exchange Online and not have any SSO, federation etc.

    I guess what I’m really asking is what are the ramifications of setting our current domain as primary in O365 but not doing anything like migrate Exchange or sync AD?

    1. Kelsey EppsKelsey Epps Post author

      There should be no ramifications as such. Right now, there is no AD Sync in place so you are using Azure AD for Office 365. Office 365 services are DNS driven, so you would have to modify DNS records for the service to become active for your employees. What are your long term plans? AD Sync?

      1. Mark

        Hi Kelsey

        thanks for the response!

        To be more precise about our environment – we have three AD and two Exchange instances. The other Exchange instance uses the domain which I will add to O365 and have our IT provider add a DNS TXT record for validation.

        So, If we did go for the option of using our two domains for user authentication in O365 would there be problems with SharePoint messages (alerts, invitations, workflows) reaching their intended recipients? Correct me if I’m wrong as I am really new to this, but in order for SharePoint messages (and that is my main concern) to reach the intended recipient’s current on premises mailbox I would need to:

        1. DISABLE the user’s Exchange Online license and
        2. set the two domains and as Internal Relay in the Exchange Online Admin Center
        (I got that tip from Franky Chen in the O365 Community yesterday. Disabling the Exchange Online license will mean that email sent to the non-existent O365 address will be sent to the on premises Exchange)

        We will certainly work toward AD Sync down the track but there are going to be some server upgrades and upgrades to Exchange in the near future, and on thinking about things and discussing with our IT service provider I am thinking it would just be easier on the users if we stick with the domain for setting up our O365 users initially.

        If we do stick with the approach for now then I assume I would need to:

        1. Leave the user’s Exchange Online license ENABLED
        2. set the and the domains as Internal Relay in Exchange Online
        2. configure email forwarding for each user’s mailbox to their current on premises address (via Outlook Web App)
        (this info also came from Franky Chen in the O365 Community)

        A little clunky I know, but we are a small outfit so that’s manageable and should mean that SharePoint e-mails end up in the user’s current on premises mailbox while we are using Then I would just need to change the two domains back to Authoritative in the Exchange Online EAC once we go with AD Sync (and not bother about the forwarding rule since O365 SharePoint will be sending to the correct address at that point).

        Thanks again for your input, and sorry this became a bit of an epic but I’m just trying to weigh up options.


  8. Sreenath Narayanan

    Hi Kelsey

    We need to transfer our existing domain to a new one for more than 50 email ids. We have both domain added successfully in office 365 exchange. We need to migrate current inbox to new one with all old emails. Is there any possible way for get back our old inbox with in the new domain for a bulk users.
    Waiting for your favorable reply.

    Sreenath Narayanan

    1. Kelsey EppsKelsey Epps Post author

      Yes. It will be the same mailbox, you just need to change the primary SMTP address on the mailbox. If you are using DirSync or AD Connect, then you will need to make the change in on-prem AD and sync to Azure AD.

      So in summary… it’s the same mailbox, but you are just changing the primary SMTP address on that mailbox.

  9. gpfnz

    Hi Kelsey, I want to re-brand our company with a new domain. We’re just using the Exchange Online plan. How do I switch over? If we want to retain the old email addresses (for say 12 months), do I need to buy a new plan and keep two plans going for the 12 month period, or can I add more than one domain on the current plan? Thanks

    1. Kelsey EppsKelsey Epps Post author

      No, you can have multiple SMTP addresses per mailbox. You will have to designate one as primary, which is also the reply to address.

  10. Paul D. Adams

    Question: If a user sets up Outlook with the onmicrosoft domain and BEFORE MX records are changed, will email automatically be diverted to the primary domain (sans the onmicrosoft domain) once the MX records ARE changed? Thanks!

    1. Kelsey EppsKelsey Epps Post author

      Mail is delivered to where the MX points it. So if you have users with a primary smtp with, it will be delivered to the mailbox where the smtp address is assigned. If that same mailbox now gets a primary address that is something different, then it will still be delivered to the same mailbox.


Leave a Reply