Promt Warning List External Users, on VB Script to checks for external users

[charli1]

Hello All,
i have the following VB Script,
It checks for external users and promts for a confirmation if it detects any email that is not listed on the domains,

Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
    Dim objMail As Outlook.MailItem
    Dim objRecipients As Outlook.Recipients
    Dim i As Long
    Dim strRecipientAddress As String
    Dim strPrompt As String
    Dim nWarning As Integer
 
    If TypeOf Item Is MailItem Then
       Set objMail = Item
       Set objRecipients = objMail.Recipients
 
       For i = objRecipients.Count To 1 Step -1
           strRecipientAddress = objRecipients.Item(i).Address
           'Change @example.com to your own company domain
           If InStr(LCase(strRecipientAddress), "@my1Domain.com") <= 0 Then
           If InStr(LCase(strRecipientAddress), "@my2Domain.com") <= 0 Then
           If InStr(LCase(strRecipientAddress), "@my3Domain.com") <= 0 Then
           If InStr(LCase(strRecipientAddress), "@my4Domain.com") <= 0 Then
           If InStr(LCase(strRecipientAddress), "@my5Domain.com") <= 0 Then
           Else
              Cancel = False
           End If
           End If
           End If
           End If
           End If
           
      Next
      
         strPrompt = "Are you sure to send this email to outside your company? "
         nWarning = MsgBox(strPrompt, vbYesNo + vbQuestion, "Confirm Email to Outside Organization")
         If nWarning = vbNo Then
            Cancel = True
         End If
      End If
End Sub

Actually in this way everything works just fine,
but i would like to modify the Promt, i would like to list all the external users on the Promt of the confirmation.,
is this possible to be integrated on this script?

Please note that i found a lot of bugs on using the following,

Const PR_SMTP_ADDRESS As String = "http://schemas.microsoft.com/mapi/proptag/0x39FE001E"

So what i'm looking for is an alternative of this.


Thank you in advance for the support.