I know this is for Exchange 2013, but I assume it works closely to how Exchange 2010 does. We are running an Exchange 2010 environment that is being used across a couple hundred+ users and multiple office locations. Our users have desktops, laptops, iPads, iPhones, Androids, etc. that are connected to their Exchange accounts. I am currently looking for a solution to some Out of Office Reply problems we are having. One of the locations that uses our Exchange system is a "sister company" that uses a different email domain than the rest of them. Just to give an example, the main email domain is "*@oil.com" and the sister company is "*@transport.com." All locations are registering to the same Windows domain, but the email domain name is different for this one company. Hope that make sense! All desktops at every site are signing into the domain, and are working flawlessly. The problem I am having is that, at this sister company, with the different email domain name, there are a few laptops that have not been added to the Windows domain. When they try to set up an Auto- Reply, they receive the Error: "Your automatic reply settings cannot be displayed because the server is currently unavailable. Please try again later." Is there any way to take care of this problem without adding all of these laptops to the Windows Domain? I know this may sound confusing, I apologize. Feel free to ask for more details. 

Hello

tip:  run Test Email Auto Configuration and check autodiscover url.