If you are synchronising your Office 365 account with your on-premises Active Directory environment, you will know that you cannot edit exchange user properties using the Office 365 administrator portal.
If you try, you will come across this error or a similar one:
In this post, I’m going to show you how to add e-mail aliases using the Active Directory User and Computers snapin.
Before we begin, make sure that you have the advanced options enabled from the view menu in ADUC.
- With ADUC open, select view, and then check the box next to “Advanced Features”
Now, with that out of the way…
- Select the user you wish to add an Alias for > Right click the name, and select properties.
- Now, Remember that advanced features check box I mentioned above, because we selected that, you will now see a tab called, “Attribute Editor”. If you don’t see this tab, go back and check the box for “Advanced Features”, and then kick yourself, for not paying attention.
- Find the variable proxyAddresses – this is the one you want to edit.
When you add new e-mail aliases, you want to make sure that your primary e-mail address will start with upper-case SMTP. Your aliases, aka, secondary addresses should be lower-case smtp.For example, I want my primary e-mail address to be email@example.com
In the proxyAddresses attribute, I would put:
As my alias, I want firstname.lastname@example.org… to do this, I will use lower case smtp:
- Apply the new settings, and click OK
- Wait patiently for your active directory to be synchronised with Office 365 (by default this happens every 3 hours but you can force this with a bit of research. – We’ll leave that for another article, here’s a link to the new ADSync tool)
Source : Azure Active Directory