MSExchangeIS Mailbox Store
Verify that the Microsoft Exchange MTA service has started. Consecutive ma-open calls are failing with error 3051.
We saw this error on a Windows Small Business Server 2003, where the "Microsoft Exchange MTA Stacks" service is disabled by default.
There were no known problems with this Exchange server as a result of this warning.
Enabling and starting the "Microsoft Exchange MTA Stacks" service appears to get rid of this warning, though we recommend simply ignoring this warning and/or excluding this event from your event log management software.
Just disabling the MTA service is not sufficient to make this error go away. See Microsoft KB810489 to see registry entries that are required.