Switch to a new domain AND have existing users send and receive mail on behalve of another domain

Occasional Contributor

Hi all!


Within a month or two my organisation will change to a new name together with a dozen of other organisations. Every organisation will have a name that adds a region to a common name. For the common name a commonname.com domain has been registered. But every organisation will also have it's own independent domain. It will be something like commonname-regionname.com.


My organisation has it's own Microsoft E2 plan for 365. Right now we are using a currentname-regionname.com as the main domain on our 365 tenant. In the new setting we want to be able to switch our E2 to the new commonname-regionname.com domain BUT we want all our users to be able to send and receive mail from the commonname.com domain. Can this be done? Will they be able to keep their mails? What about the Sharepoint, Onedrive, Azure AD-added applications and devices? How should we proceed to make it all happen? If it were to be just switching to a new domain, it wouldn't be too hard to figure out. But with the commonname mail-domain, it 's not clear to me what to do. Any help appreciated!




10 Replies

You are not giving us the most important information - are all those organizations using the same O365 tenant or do they have separate ones? Within the same tenant, changing domain is a fairly straightforward operation. But if there are multiple tenants involved, the process can get very complicated and will most likely involve third-party tools.

@Vasil Michev Thank you for the time you spent in answering! It 's te complicated case I 'm afraid. We have all seperate tenants. The organisation that will be hosting the common name isn't even on a 365 tenant. 

So is the end goal to merge them all in a single tenant, or keep separate tenants? Currently, there is no possibility to "share" domain between multiple tenants, so the latter scenario will be much harder to accomplish. There is some work being done by Microsoft in this space, as detailed here: 


But this is still in preview, and until it is released, your best bet are third-party tools. The same is true for the "merge" scenario btw, the native Microsoft tools to do such a project are lacking...

@Vasil Michev No we will be on our independent 365 or google-suite cloud tenants. BUT the common domain won't be used on a mailserver. Normally on that hosting there will be only made alias users forwarding to our region domain. Does that make it simpeler? 

There is no way to "share" a domain between multiple tenants, apart from the preview I mentioned above.

@Vasil Michev OK. I wil study the video som more. Thank you for looking into this...

@Vasil Michev  I was looking at the roadmap of 365 and found out that this very month it will be possible to select the option to send from a different domain. The addressee will see the selected address as the sent from address. Do you think that together with this change it will be possible to add one domain to multiple tenants?


If this wouldn't be the case, what kind of 'third party' solution would be advisable?

Hi @Paul Vandeweerdt, I know almost nothing about MS plan, but meanwhile you can try to use this:



@Vasil Michev As 'verified'  alias domain, only, I mean. Without the mx record of the shared domain pointing to all these tenants. If I 'm informed well, organisations using Google Suite are able to share a common domain without problems  when creating aliasses for the users on the shared domain ... 

@Paul Vandeweerdt that's a different feature, nothing to do with domain sharing.