Exchange 2010 OWA and Mobile Devices unable to Reply, Reply to All, or Forward messages

I recently ran across a known bug with Exchange 2010 SP1. The issue was with OWA and Mobile devices. They were unable to Reply, Reply to All, or Forward messages. From OWA you would receive a message┬ásimilar┬áto the one below, titled “An unexpected error occurred and your request couldn’t be handled”. About halfway down the error message you would see the text “must be a valid domain name”.

Mobile devices would notice that all messages other than new messages they tried sending out would be stuck in their Outbox.

Ends up the issue is with the one of your Accepted Domains. You can’t have any spaces in the “Name” field of an Accepted Domain. Doesn’t matter if it had been working for several months without any problem or not… has to be renamed without any spaces.

For myself, this issue popped up for one of my clients running SBS 2011. They had a default Accepted Domain that had the name of “Windows SBS External Domain”. (3 spaces in that…) By simply running the powershell command below, I was able to rename the Accepted Domain to not include any spaces. After about 15 minutes (or a reboot of the Exchange Server…) the issue went away. Any messages in the Outbox on mobile devices will then be processed.

Set-AcceptedDomain -Identity “Windows SBS External Domain” -Name “WindowsSBSExternalDomain”