The E-mail Router service could not run the service main background thread

Well I found in a Microsoft Dynamics CRM 4.0 rollup 10 with email router (on-premise) deployment that the email router service was stopped. I tryed to start the service and I couldn' t. I looked at event viewer and I found this log:

#16192 - The E-mail Router service could not run the service main background thread. The E-mail Router service cannot continue and will now shut down. System.Configuration.ConfigurationErrorsException: The E-mail router service cannot access system state file Microsoft.Crm.Tools.EmailAgent.SystemState.xml. The file may be missing or may not be accessible. The E-mail Router service cannot continue and will now shut down. ---> System.Xml.XmlException: Root element is missing.
   at System.Xml.XmlTextReaderImpl.Throw(Exception e)
   at System.Xml.XmlTextReaderImpl.ParseDocumentContent()
   at System.Xml.XmlLoader.Load(XmlDocument doc, XmlReader reader, Boolean preserveWhitespace)
   at System.Xml.XmlDocument.Load(XmlReader reader)
   at System.Xml.XmlDocument.Load(String filename)
   at Microsoft.Crm.Tools.Email.Providers.ConfigFileReader..ctor(String filePath, ServiceLogger serviceLogger)
   at Microsoft.Crm.Tools.Email.Providers.SystemState.Initialize(ServiceLogger serviceLogger)
   at Microsoft.Crm.Tools.Email.Agent.ServiceCore.InitializeSystemConfiguration()
   --- End of inner exception stack trace ---
   at Microsoft.Crm.Tools.Email.Agent.ServiceCore.InitializeSystemConfiguration()
   at Microsoft.Crm.Tools.Email.Agent.ServiceCore.ExecuteService()

After some search I found here that file Microsoft.Crm.Tools.EmailAgent.SystemState.xml was corrupted. I deleted the file and started the email router service.