Exchange Authentication Question

Hello AD/Exchange experts.
I am setting up a new DC/Exchange 2013 Server for a company with several split businesses and email domains. Here is my question.

I would like all users to login to OWA using their SMTP email address and NOT the AD Domain Name.

I setup a new Windows 2012 DC with the AD Domain as COMPANYX.COM and I can get all users to login with however I am not able to have them login using the SMTP address (ie.

Is this possible to accomplish out of the box ? I have no problem with email flow, I have setup multiple authorize SMTP policies and setup the appropriate reply-to addresses with no issues, I am just struggling with the AD authentication portion.

Who is Participating?
Simon Butler (Sembee)Connect With a Mentor ConsultantCommented:
There is no link between the email domain and the Windows domain.
However you can make them the same.
You need to add the email domains as additional UPNs.

AD Domains and trusts.
Right click and Choose Properites.
Click on the UPN Suffixes tab and add away.

The adjust the settings on the account in ADUC.

Note that if you change the email address then you have to adjust the UPN yourself.

s3e3Author Commented:
Perfect, thank you to both of you. Worked like a charm.
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