Since I can't comment yet - @LanceBaynes - The answer by Mat is correct. The user will be locked out, which is not a problem but a security measure to prevent users that haven't used their account for a long time (for example got fired), not to be able to access their accounts by changing passwords if they gained access somehow to a workstation inside the company. The password can be changed anytime by the administrator once the maxexpired time is over.