Exchange 2010 - Domain choice for OWA login? Or alternative strategy?

I am working with Exchange 2010 currently and am wondering how having a domain/sub-domain logon choice being presented on the logon page can be achieved.
Is there anything configurable that exists already within Exchange to enable such a feature? An admin had something on the logon.aspx page but it appears to get wiped out/overwritten by Exchange 2010 periodically and am not sure how.

Basically there is a domain,, and a sub-domain,, within the same Forest.
Exchange 2010 serves user/mailboxes in both domains.
When a user logs into the Outlook Web Access, we'd prefer them not have to manually type their domain each time (like domain\username, or sub-domain\username), but instead be easily able to login.

From what I understand the logon.aspx page or related files may need to be customized here:
C:\Program Files\Microsoft\Exchange Server\ClientAccess\Owa\auth

There are some duplicate usernames between the parent domain and child domain, so we can't have it just be the username because if it's "JSmith" and there's a "JSmith" in both domains, then it won't work.
So if they could have a radio button, or a drop-down menu, that lists "domain" or "sub-domain" which would prepend or append to the username box accordingly, I think that would be ideal.
Unless there's another way?
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

AmitIT ArchitectCommented:
Can you check this, you need to enable Username setting. Browse to:

 Open EMC>Server Config>Select CAS Server>OWA>Properties>Authentication>Click on Use Form based authentication>Username Only.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
garryshapeAuthor Commented:
"User form-based authentication"  is selected, along with "Domain\Username" as the logon method, however, it doesn't appear that when user access the login form that they can click or select an option to choose which domain they wish to logon to. That's what I'm looking to offer to the user when they logon so that they don't have to manually type their domain.
Ideally we could have a radio button or drop-down menu that automatically types in "domain\" or "sub-domain\" into the username box ?
AmitIT ArchitectCommented:
If you change it to username only and select the Domain, where Exchange is installed. You can just login with your Account name. Like if you are currently entering. domain\username. After change, you can just use username. Rest Exchange will take care. You can test in your lab.
Big Business Goals? Which KPIs Will Help You

The most successful MSPs rely on metrics – known as key performance indicators (KPIs) – for making informed decisions that help their businesses thrive, rather than just survive. This eBook provides an overview of the most important KPIs used by top MSPs.

garryshapeAuthor Commented:
What happens is if I do that and I choose the domain "", then users who exist on will still have to specify "sub-domain\username" format when they sign in.
We don't have separate mailbox login URL for users on separate domains, but they do all have the same ending e-mail address
AmitIT ArchitectCommented:
Sub-domain means child domain right? Where is your Exchange server installed. Remember you can have only one Exchange Org.
garryshapeAuthor Commented:
Yeah we have as the domain name and the child domain, So AD users are managed separately in

For Exchange 2010, it is just one Exchange organization that is comprised of mailboxes within the entire scope of the forest to include the domain and its child domain.
AmitIT ArchitectCommented:
So, here are the details, I am able to collect for this issue. If you use username only option and whatever domain you select, those user don't need to enter domain name. Example, you opted for parent domain, then child domain user still need to enter domain name. Read this:
garryshapeAuthor Commented:
Ok thanks for the feedback
I guess at this point the best way to go would be UPN login? That way users login with their e-mail address? because e-mail address is unique?
AmitIT ArchitectCommented:
Yep, that could be best option in your case.
garryshapeAuthor Commented:
ok thanks for the feedback. sounds like a better way to go than html hacking up the login page.
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today

From novice to tech pro — start learning today.