I came across a blog post which details issues with Exchange 2010 when deployed in a domain that has a “dot” in its NETBIOS name.
Launching EMC 2010 and clicking on “Exchange On-Premises” displays the following error:
“The following error occurred when getting user information from ‘domain.comusername’: The operation couldn’t be performed because the object ‘domain.comusername’ couldn’t be found on domaincontroller.domain.com. It was running the command ‘Get-LogonUser’.
The issue will be fixed in the next update rollup (UR4) for Exchange 2010. You can call Microsoft Support for a custom fix if you have already deployed 2010 in production.
More info @ source