Newbie O365 Question - Creating New Users

Occasional Contributor

Hello, this is a newbie question so I apologize in advance for the entry level post.


I am a small business owner with 35 employees. I am currently using on premise exchange to host email. I plan to migrate mail to Office 365 in 3 months (after busy year end).


However, I want to get all my users up and running with the O365 Office Suite (Word, Excel, PowerPoint etc) and Microsoft Teams in the next few weeks.


I have already added my domain to O365.


I also already have 11 users setup with O365 Business Premium licenses. These users were setup on the domain NOT my domain. EG their username's are


My question is this....Should i create the new users right now on the domain OR my domain. Given the fact that I am not going to migrate my email to O365 for another 3 months does it matter what domain I create these new users under now in order to get them up and running with the Microsoft Suite and Teams?


Let me know, thank you!



10 Replies
You are not planning to run sync from AD to Azure AD?
You can create them and use your custom domain! Your mail will not be affected!
I was hoping to scratch AD altogether and use Azure AD for identity management and single sign on. We have a fairly lean IT infrastructure: 1) On premise exchange which will migrate to O365 2) On premise file server which will migrate to sharepoint/OneDrive 3) We do use the domain controller for basic group policy but its my understanding that Azure AD can handle this (could be wrong) 4) We use Sugar CRM which i understand can be linked to Azure AD for SSO Other than that, we don't really have much....
Ok! Yes you could join your devices to azure ad for sso! You don’t have gpo’s in azureAD but if you have win10 you can use Intune to push policy’s and apps and so on! It all depends on what your demands are

Thanks for your reply! So, just to clarify from the initial question, creating the new user on my domain in the O365 admin portal will be fine....?


I assume i'll have to change the usernames of the existing users from the domain to my domain once i migrate email...?

It doesn’t really matter when you do it! You can change them now or later, or just add an alias
You will be losing a bit of functionality by not moving Exchange workload first. Most orgs go OneDrive or Exchange first, then go for the other things such as Share Point / Teams etc. as they go hand in hand and piggy back off Office 365 groups.

Here are some examples of features you can't use or get when keeping Exchange Online on Prem:

Also before Teams you'll want to get OneDrive going since it integrates pretty heavy into Teams along with SharePoint:

You could be asking for some routing headaches and Outlook client issues trying to load you Office 365 mailboxes if you enable your licenses. I would suggest you hold off on turning Exchange Online licenses on until you're ready to Migrate. Since you would be doing a cut over migration you would have to have some downtime and time to import all the mailboxes across for when you swap your domain routing over as well.

If you setup Hybrid you could do this a few users at a time.
Thanks for your help. I appreciate it.
I would recommend to disable EXO license for your users so you are sure you don't have any kind of problems in regards of e-mail. Another important thing: what version of Exchange do you have OnPrem? I'm asking this because your idea of avoiding to deploy directory synchronization...depending on your source Exchange and the migration method chosen, you will need to set up a directory syncrhonization
Thanks for the resources, Chris. I’ll have a read through them today.

Thanks for the advice on taking the EXO licences off for each user. I'll do that.


We're currently running Exchange Server 2010...