Event ID 15006 or 15007 on Exchange 2010 Hub Servers

During high peaks of email, especially during the holiday season, you may notice delay notifications stating that email has been queued and/or delayed. When this happens, check the Exchange 2010 HUB servers for the following events: Event ID 15006 or 15007

Event log entry for critically low available disk space
Event Type: Error
Event Source: MSExchangeTransport
Event Category: Resource Manager
Event ID: 15006
Description: The Microsoft Exchange Transport service is rejecting messages because available disk space is below the configured threshold. Administrative action may be required to free disk space for the service to continue operations.

Event log entry for critically low available memory
Event Type: Error
Event Source: MSExchangeTransport
Event Category: Resource Manager
Event ID: 15007
Description: The Microsoft Exchange Transport service is rejecting message submissions because the service continues to consume more memory than the configured threshold. This may require that this service be restarted to continue normal operation.

This means that your HUB server/s are experiencing “backpressure”. Backpressure is a new ‘feature’ in Exchange 2007 / 2010 where Exchange actually monitors resources such as Free Disk Space on the disk where the Exchange Message Queue / Message Queue Transaction Logs live and the Memory that the Edgetransport.exe process is using and memory in general used by other processes.​

How To Get Mail-Flow Restored Temporarily?
1. On the HUB Server/s in question, navigate to c:\program files\microsoft\exchange server\v14\bin​\edgetransport.exe.config
2. Open the edgetransport.exe.config​ using Notepad and search and change the “EnableResourceMonitoring” from “True” to “False”
3. Save and close the file
4. Restart the Microsoft Exchange Transport Service

Once email is flowing again, you can begin to address the resource issue with the HUB server.

References
Experts-Exchange