I started studying for the MCSA: Office 365 and about 30 minutes in I started having problems. The initial signup was smooth and I was able to add a couple users and associate my domain. However, after trying to change the primary address and username is when the problems began and I’ll try to document it the best I can here as I couldn’t find much on this particular error from my searching but it was pretty self-explanatory so started digging.

First off, as I’m sure you’re aware when signing up for Office 365, is that it will use the yourcompany.onmicrosoft.com domain as the primary address and username. From the Office 365 Admin center, when I went in and tried to change or even add a new address as an alias, it would error with “A parameter cannot be found that matches parameter name ‘EmailAddresses’” Since I was unable to do it from the Office 365 Admin Center, I decided to go ahead and launch the Exchange Admin Center and try to add the address through there first.

After navigating to the mailbox and the email address area, I added the address I wanted and set it as my Reply-To address. I confirmed in the EAC, sethhall@mcsa365lab.com was now set as my primary address and when I went back to the Office 365 Admin Center > Active Users, the new address was primary with the *.onmicrosoft.com as an alias, but I still had to change my username though. Luckily, it looks like the change through the EAC let me update the username without any issue and I was able to get it set.

I didn’t take any screenshots while doing mine so I’ve included a few screenshots on another object that gave me the same problems and that I was able to fix the same way.



Looking at Active User, username will be the name@yourcompany.onmicrosoft.com which we want to change to name@yourdomain.com






We click on the user and it brings up the properties page and we’ll go into Edit on the username and try to first add an alias and click Add.







After clicking add, we’ll see this error. This occurred for me even if I tried to Set as Primary right away or added the alias and then tried to Save Changes, it wouldn’t take either one.




We go into the EAC and double click the mailbox we want to change.







Double clicking brings up the mailbox settings and we’ll go to Email Address. Cick the + and you’ll get another popup.







If you want to change the primary address from here then leave the SMTP bubble selected and be sure the “Make this reply address” box is checked. If you just want to add an SMTP alias then leave SMTP selected and be sure to UNCHECK the “Make this the reply address” box.





Primary address updated, previous mcsa365lab.onmicrosoft.com address now an alias. Save this and get back to the EAC to confirm the changes. We’ll then switch back over to the Office 365 Admin Center




You’ll need to refresh the view to see the address change on the Active Users view or click the user in question to bring up their properties. From there you can confirm the primary address and alias have been added/changed and also change the username if you wish to.





We can now see that we’ve change the users username/sign-in address to our own domain.

So all in all, not too complicated but maybe it’ll help someone else who runs into this issue.


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