When you start your email router service and you get an error like this:
The Microsoft CRM Email Router service on Local Computer started and then stopped. Some services stop automatically if they are not in use by other services or programs.
Please delete this file.
C:\Program Files\Microsoft CRM\Email\Service\Microsoft.Crm.Tools.EmailAgent.SystemState.xml
After deleting the file , you can start your emailrouter service and system will create this xml again.