You are not supposed to use the discovery service for the email router - but the unique URL for your organization
You can find it in CRM under Customization - > Developer resources
Follow the instructions here:
http://social.technet.microsoft.com/wiki/contents/articles/4686.microsoft-dynamics-crm-e-mail-router-configuration-crm-2011-online-exchange-online.aspx
Good Luck
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