FIM Service - Problems with Exchange Mail Listener

I have a lab environment with Exchange 2010 (exchange) and FIM 2010 R2 (fimserver), both running on Windows Server 2008 R2 Std SP1. My problem is that the Exchange Mail Listener in the FIM Web Services is throwing exceptions and unable to poll or send mail. The exception is always "System.InvalidOperationException: Client found response content type of '', but expected 'text/xml'."

Versions:

FIM Service: 4.1.3419.0

Exchange 2010: 14.01.0218.013

The FIM service is ran under a service account "Domain\fimservice", and has an Exchange 2010 mailboxfimservice@domain.com. The "Microsoft.ResourceManagement.Service.exe.config" is defined as following:

<appSettings><!-- Setup adds entries --><add key="mailServer" value="https://exchange.domain.com/ews/exchange.asmx" /><add key="isExchange" value="1" /><add key="sendAsAddress" value="FIMService@domain.com" /><add key="synchronizationServerName" value="fimserver.domain.com" /></appSettings>

On the FIMServer I can run IE under the FIMService account and successfully get tohttps://exchange.domain.com/ews/exchange.asmx without any certificate errors or authentication prompts. I can also access OWA and send and recieve mail from the fimservice account.

Turning on additional logging on the web services I see the following messages:

Microsoft.ResourceManagement Verbose: 0 : The Exchange Mail Listener is marking Microsoft Exchange "Read" messages as "Unread".
    ThreadId=11
    DateTime=2013-12-03T19:45:31.5391601Z
Microsoft.ResourceManagement Verbose: 0 : The mail listener is looking for items that match this search expression: Find Item:
	(((((exists(ilmStatus) and (ilmStatus is equal to 'Read'))) and (((((((ItemClass is equal to 'IPM.Note.IdentityManagement.AddToGroups') or (ItemClass is equal to 'IPM.Note.IdentityManagement.RemoveFromGroups'))) or (ItemClass is equal to 'IPM.Note.IdentityManagement.ApprovalResponseApproved'))) or (ItemClass is equal to 'IPM.Note.IdentityManagement.ApprovalResponseRejected')))) and ((not(exists(ilmApprovalEndpoints)) or (
    ThreadId=11
    DateTime=2013-12-03T19:45:31.5470841Z
Microsoft.ResourceManagement Error: 3 : System.Web.Services: System.InvalidOperationException: Client found response content type of '', but expected 'text/xml'.
The request failed with an empty response.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at Microsoft.ResourceManagement.WebServices.Mail.Exchange.ExchangeServiceBinding.FindItem(FindItemType FindItem1)
   at Microsoft.ResourceManagement.WebServices.Mail.Exchange.MailChannel.ExchangeMailChannelListener`1.ExchangeMailListener.<OnPollTimerExpired>b__0(Boolean findUnreadItems)
   at Microsoft.ResourceManagement.WebServices.Mail.Exchange.MailChannel.ExchangeMailChannelListener`1.ExchangeMailListener.OnPollTimerExpired(Object state)

Here is another instance:

Microsoft.ResourceManagement Verbose: 0 : The Exchange Mail Binding is creating binding elements.
    ThreadId=14
    DateTime=2013-12-03T19:45:32.7624276Z
Microsoft.ResourceManagement Error: 3 : System.Web.Services: System.InvalidOperationException: Client found response content type of '', but expected 'text/xml'.
The request failed with an empty response.
   at System.Web.Services.Protocols.SoapHttpClientProtocol.ReadResponse(SoapClientMessage message, WebResponse response, Stream responseStream, Boolean asyncCall)
   at System.Web.Services.Protocols.SoapHttpClientProtocol.Invoke(String methodName, Object[] parameters)
   at Microsoft.ResourceManagement.WebServices.Mail.Exchange.ExchangeServiceBinding.FindItem(FindItemType FindItem1)
   at Microsoft.ResourceManagement.WebServices.Mail.Exchange.MailChannel.ExchangeMailChannelListener`1.ExchangeMailListener.<OnPollTimerExpired>b__0(Boolean findUnreadItems)
   at Microsoft.ResourceManagement.WebServices.Mail.Exchange.MailChannel.ExchangeMailChannelListener`1.ExchangeMailListener.OnPollTimerExpired(Object state)
    ThreadId=4
    DateTime=2013-12-03T19:45:32.7644086Z