Overview:
Follow the guide below to configure Microsoft Exchange 2007 and Microsoft Exchange 2010 to use mx1.securolytics.io and mx2.securolytics.io as the SmartHosts and Internet Mail Relay.
 

• Open Exchange Management Console
• Click on the + next to Organization Configuration
• Select Hub Transport
• Select the Send Connectors tab:  (If you do not see the Send Connections tab click View - Add/Remove Columns...) to display it)
  

• Right-click on the existing Send Connector and select Properties
• Click on the Network tab.
• Select "Route mail through the following smart hosts:"
• Click Add

• Enter mx1.securolytics.io as the first smarthost as shown below and click OK
  

• Add mx2.securolytics.io using the same procedure.  Both smarthosts should be listed.
  
• Click Apply
• Click OK

These changes will take effect immediately without need to reboot the server or restart any services.