There are 2 common issues with Microsoft CRM Email Router:

1. The service “Microsoft CRM Email Router” does not start.

2. The router routs old Emails.

Both issues are related to a file located at: “C\Program Files\Microsoft CRM Email\Service\ Microsoft.Crm.Tools.EmailAgent.SystemState.xml”

If the file is corrupted the router will not start. Stop the router service, rename the file and start the router service again. In most cases this will solve the problem

The file also maintains a timestamp as xml parameter named “ThresholdDate”.
By default this value is “0001-01-01T00:00:00.0000000Z” (format as “YY-MM-DDTHH:MM:SS.mZ).
Each time the user’s mailbox is scanned, the timestamp is incremented / updated. To eliminate scanning old emails, set the date and time to current date / time.
Example: The 10^th February 2010, 11:45 is set as: 2010-02-10T11:45:00.0000000Z