Mimecast MSO Username Error Fix. If you are a Mimecast user and are also using Windows 8.1, you may find that when you have installed the Mimecast client for Outlook (MSO) and try to enter your domain or cloud credentials, the username has SMTP set and cannot be changed and the password part is greyed out. We have created this MSI fix that will solve this issue for you and you can then use this MSI on a large scale basis to push out using Group Policy, Configuration Manager or WDS. Please see our website for full instructions about using this program.
Download and use it now: Mimecast MSO Fix