Can not set up Outlook using mydomain.ca but can using mydomain.onmicrosoft.com - Office applications - Office 365

I have successfully registered my domain and have it hooked in to Office 365. We are sending and receiving emails without issue. My problem is configuring Outlook whether it be 2007 or 2010. I have downloaded all the connection tools and patches, logged in to OWA and completed the setup in there. When using the autodiscover, per MS instructions, I enter in the username as user.name@mydomain.ca and it won't connect. This is the only logon/email that I have set up for my test user. If I enter in the username of user.name@mydomain.onmicrosoft.com, autodiscover finds it and then asks me to login, for which I use user.name@mydomain.ca and it works. For the record, I did not create the user.name@mydomain.onmicrosoft.com.

When I give instructions out to my users, many of which are remote, I want to be able to tell them to use their email address not the onmicrosoft one - I would prefer not to have this at all ideally. What am I doing wrong here? I am also concerned that if as and when I try to do domain federation and SSO that I might run in to some problems.

Hello canadastew,

I'm sorry to hear that you are having trouble configuring Outlook for Office 365 with your vanity domain and have to use your ".onmicrosoft.com" domain. You should check to see how the "user name" and "e-mail address" of your users are configured in the Office 365 portal at https://portal.microsoftonline.com

Sometimes users are created by DirSync with the ".onmicrosoft.com" domain instead of your vanity domain and must be manually changed with PowerShell following the steps from the following articles to resolve this issue:
http://support.microsoft.com/kb/2523192 (DirSync users show O365 domain - Article)
http://www.microsoft.com/showcase/en/us/details/ec7bbfeb-d07f-48c1-bb09-25be86aa4210 (DirSync users show O365 domain - Video)

Otherwise this could still just be an autodiscover issue which you can troubleshoot with the following articles:
http://support.microsoft.com/kb/2404385 (Adding a CNAME autodiscover DNS record to configure Outlook)
http://support.microsoft.com/kb/2581088 (Other OUtlook issues when autodiscover is not setup correctly)
http://support.microsoft.com/kb/2566899 (Issues preventing Outlook from configuring)
http://support.microsoft.com/kb/2410859 (Firewall prevents connection to Office 365 to configure Outlook)

Please let us know if you are able to get this issue resolved or if you need more help so that I can update this thread with any additional information you may need.