One of the smaller networks I manage consists of a handful of users who connect to a SBS 2003 server. Their server keeps reporting the following in the Windows Application Log:
Source: MSExchangeIS Mailbox
“Verify that the Microsoft Exchange MTA service has started. Consecutive ma-open calls are failing with error 3051″
This error would lead you to believe that the MTA Stack service wasn’t started when it should be. But if this is the only Exchange server in your organization and you aren’t connecting to an X.400 mail server, the MTA Stack service is not necessary. Previously I had even changed this service’s startup type to disabled, yet the server continued to report this error.
KB 810489 explains that stopping and disabling the Microsoft Exchange MTA Stack service is not sufficient to resolve this error. Two registry entries need to be created on the server for each public or private database on the server.
Open the following key in regedit:
For each private or public database that is listed under this subkey, perform these steps
1) Right click on the database, select New – DWord Value. Name the value Gateway In Threads
2) Set the Gateway In Threads value to 0 (zero)
3) Right click on the database, select New – DWord Value. Name the value Gateway Out Threads
4) Set the Gateway Out Threads value to 0 (zero)
You must restart the Micrsoft Exchange Information Store service for the changes to take effect. The KB also explains:
“When you set the Gateway In Threads value and the Gateway Out Threads value to 0, Store and MTA connection failure events are not logged in the Application log after the MTA Stacks service has been disabled. If you create a new database on the server, you should set the Gateway In Threads value and the Gateway Out Threads value for the new database.”