Searching SentItems for DisplayName instead of Email Address

I have an EWS application that searches the SentItems folder for emails after a certain date, and by specific email addresses. I’m having a problem in finding messages that I have responded to as opposed to new messages.

Example: I’m sending a new message to John Smith, so I send a message to johnsmith@someisp.net

In my code, I’m using the following logic to search the SentItems folder for any messages sent to John:

Dim lstEmailAddrTo As New List(Of SearchFilter)
For Each strEmailAddress As String In 	lstEmailAddr.AsEnumerable
  lstEmailAddrTo.Add(New SearchFilter.ContainsSubstring(EmailMessageSchema.DisplayTo, strEmailAddress))
  lstEmailAddrTo.Add(New SearchFilter.ContainsSubstring(EmailMessageSchema.DisplayCc, strEmailAddress))
Next

Dim sfltrEmailAddrTo As SearchFilter = New SearchFilter.SearchFilterCollection(LogicalOperator.Or, lstEmailAddrTo.ToArray())

Dim lstSentItems As New List(Of SearchFilter)
lstSentItems.Add(New SearchFilter.IsGreaterThanOrEqualTo(ItemSchema.DateTimeSent, dteSent))
lstSentItems.Add(sfltrEmailAddrTo)

Dim sfltrSentItems As SearchFilter = New SearchFilter.SearchFilterCollection(LogicalOperator.And, lstSentItems.ToArray())

The problem is that it is not picking up messages that I have responded to a message from John…When I manually view the MailItem in Outlook, it appears that Outlook creates a "Contact" like entry and instead of 'johnsmith@someisp.net' in theTo field , it displays 'john smith'

Any ideas would be greatly appreciated.
Thank you in advance for your time.

Sincerely,
Paul Goldstein

Paul D. Goldstein Forceware Systems, Inc.