Migrate mailbox to another domain same Tenant

[gteibo1]

Hi, 

In our company, we bought a new domain and we want to move all of our existing mailboxes to the new one.

I already have both domains registered in the same tenant.

I mean support@contoso.com to support@contosola.com etc.

May you please give me any advice on the best way to perform this?

[#2]

There's no need for "migration". All you need to do is change the Primary SMTP address to point to the new domain, as well as any other attributes that make sense for your scenario (UPN for example).

[#3]

Migrating existing domains between two Office 365 tenants.
Step 1: Disable the ADFS Federation. This step only applies to tenants with one or more domains using identity federation.
Step 2: Disable Azure Active Directory Connect synchronization.
Step 3: Change all UPNs to the .onmicrosoft.com domain.
Step 4: Remove any dependency.

[#4]

@gteibo1Hi there! 

Your description is a bit vague, lets see if i understood you correctly:

A)

You have a tenat X and you are NOT going to setup a new tenant but just register a DOMAIN in the existing tenant x and want to change the UPN so that the users receive mail with the new Domain name?

OR

B)

You want to physically move mailboxes between Tenants?

Two totally different things here, let me know what you actually want to achieve and am happy to help. Done some 300+ migrations so might be able to help you :)

EvilSecurityFellow

[#5]

@EvilSecurityFellow 

Hi we are also doing a migration from one Office 365 tenant to another in batches. the UPN is changing because they use firstname.lastname@domain.com

Source was firstinitial.lastname@domain.com

I have a question about Resource Room Mailboxes. Has anyone dealt with that. 

Like how to handle Meeting Rooms when you migrating from Office 365 to Office 365 and your domain and upn are changing actually

Thanks

[#6]

Mover.Io is an amazing tool for quick migrations

[#7]

@Lewis-H That sounds very wrong, why would the OP need to disable federation and ADSYnc, that will break some Integrations

[#8]

@gteibo1 

How about cross-tenant mailbox migration?

Cross-tenant mailbox migration - Microsoft 365 Enterprise | Microsoft Learn