Having installed the CRM 2011 Email Router on the server and configured the Incoming and Outgoing server options when I came to ‘Test Access’ I got the following error in both test results:

Incoming Status: Failure - Type 'System.ServiceModel.Channels.ReceivedFault' in Assembly
'System.ServiceModel, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' 
is not marked as serializable.

To solve this problem I had to do two things:

1. I changed the router service account (the account that is configured to run the email router service) to a valid domain user.
2. Since I was using the Access Credentials of Other Specified for the profiles the router service account needed to be added to the PrivUserGroup.

Once I had made these changes and restarted my CRM Email Router Service then the Test Access dialog indicated that both Incoming and Outgoing profiles had succeeded.