Exchange remote Connectivity Test Failing: The remote certificate is invalid according to the validation procedure.

Trying to run this test: Microsoft Exchange Web Services Connectivity Tests
Synchronization, Notification, Availability, and Automatic Replies (OOF)

Getting this error:

Exchange Web Services synchronization, notification, availability, and Automatic Replies (OOF).
 	Not all of the tests of Exchange Web Services tasks completed.
 	
	Test Steps
 	
	Ensuring that the test mailbox folder is empty and accessible.
 	ExRCA couldn't confirm that the folder is accessible and empty.
 	
	Additional Details
 	Exception details:
Message: The request failed. The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
Type: Microsoft.Exchange.WebServices.Data.ServiceRequestException
Stack trace:
at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request)
at Microsoft.Exchange.WebServices.Data.MultiResponseServiceRequest`1.Execute()
at Microsoft.Exchange.WebServices.Data.ExchangeService.BindToFolder[TFolder](FolderId folderId, PropertySet propertySet)
at Microsoft.Exchange.Tools.ExRca.Tests.EnsureEmptyFolderTest.PerformTestReally()
Exception details:
Message: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
Type: System.Net.WebException
Stack trace:
at System.Net.HttpWebRequest.GetResponse()
at Microsoft.Exchange.WebServices.Data.EwsHttpWebRequest.Microsoft.Exchange.WebServices.Data.IEwsHttpWebRequest.GetResponse()
at Microsoft.Exchange.WebServices.Data.ServiceRequestBase.GetEwsHttpWebResponse(IEwsHttpWebRequest request)
Exception details:
Message: The remote certificate is invalid according to the validation procedure.
Type: System.Security.Authentication.AuthenticationException
Stack trace:
at System.Net.TlsStream.EndWrite(IAsyncResult asyncResult)
at System.Net.ConnectStream.WriteHeadersCallback(IAsyncResult ar)

I do have a valid certificate issue by RapidSSL, I have followed the instructions to install it to my exchange and to IIS, I have used the RapidSSl tester to verify the cert is installed.  The cert is to mail.dixiedigital.com.  All the pointers in exchange (that I can find, under Management Console > Server Configuration > Client Access > Right click each one, set external URL to https://mail.domain.com/[the thing that supposed to be here]) are set correctly I think.  

Not sure what to do, I have googled it, but most issues revolve around the certificate being self-signed.  I don't know where to go to find my issue from here.

**Text edited per users request** -JARmod101