Cannot Create Mailbox In Exchange – Property Expression Isnt Valid

When trying to add a Mailbox to a user in Exchange 2010 or Exchange 2007 you may come across the following error.To view a video of the solution head to the end of the article.

As seen here.

property expression isnt valid exchange mailbox

This is because in AD the users User Logon Name is ot assocaited with the FQDN for you domain, if you read the error it actially says it in a roundabout Microsoft way. To fix this do the following.

Go into Active Directory users and Computers the right click the user in question and select properties then Account.

Next to User Logon Name you will see a drop down menu. Select it and then select your domain.

Cannot attach mailbox to to user property expression

Now when you try and add a mailbox to your user you will be able to complete the task successfully.