In our hybrid environment, we have a single on-premises Exchange 2010 SP3 UR8 server.  This server hosts approximately 80% of mailboxes.  The remainder are on Office 365.  Currently, MX and autodiscover for xyz.com domain point to the on-premises server.  There are no major issue with the setup.

My question is around free\busy.  We have federation setup with several 3rd parties.  This works fine for both on-premises and O365 based mailboxes.  The complication is around the domain.  For on-prem mailboxes, free\busy using john.smith@xyz.com works but not for our office 365 mailboxes.  The 3rd party organistion has to create a contact using the format john.smith@xyz.mail.onmicrosoft.com.  Described in detail here http://blogs.msdn.com/b/mvpawardprogram/archive/2014/01/27/calendar-federation-with-an-exchange-hybrid.aspx

Is there a way to proxy these requests to Office 365 using just the @xyz.com domain?

Thanks in advance

Steve

Hi Steve:

Thanks for posting your question here. But this forum is focusing on Office client. For Office 365 federation related question, this community will be the best place to post. Thank you.