If you are on Windows Server 2003, install <a href="https://technet.microsoft.com/en-us/library/security/ms10-024.aspx" rel="nofollow">https://technet.microsoft.com/en-us/library/security/ms10-02...</a> with /b:SP2QFE, otherwise your mail server may stop working. (Yes, installing <a href="https://support.microsoft.com/en-us/kb/957047" rel="nofollow">https://support.microsoft.com/en-us/kb/957047</a> should do this for you, but this is safer especially considering how Server 2003 don't use CBS servicing)