I try to schedule Exchange Server system maintenance for times when no users will need access, but no matter when I do it, people still log on to the Exchange Server while I'm working on it. How can I stop them?

A. A registry subkey lets you restrict who may log on to the Information Store (IS) of your server. When this subkey is in place, only users whose distinguished names (DNs) appear in the subkey’s value can log on. Everyone else sees a dialog box that says that their logon failed. To make this work, add a REG_MULTI_SZ value named Logon Only As to HKLMSYSTEMCurrentControlSetServicesMSExchangeISParametersSystem. Then add the full DNs of the accounts that should be able to log on, including the organization, site, and recipient container names. For example, /o=RA/ou=USA-East/cn=recipients/cn=PaulR specifies that a user named PaulR in the recipients container of the USA-East site in the RA organization can log on. One final note: you must stop the IS before making this change, then restart it when you're done.