Flag email going to multiple different external domains using VBA - vba

Question

We are trying to read the domains of addresses an email is being sent to, and if there is more than one domain, confirm that the user wants to send the email. That way we don't risk confidentiality by sending an email to a wrong domain.
We developed a macro that flags all emails being sent to a different domain as external, and gives a popup box that asks "Yes or No". We want to modify to flag only if there is more than one external domain.
For example, flag #google.com, #yahoo.com and not #google.com, #google.com
Private Sub Application_ItemSend(ByVal Item As Object, Cancel As Boolean)
Dim recips As Outlook.Recipients
Dim recip As Outlook.Recipient
Dim pa As Outlook.propertyAccessor
Dim prompt As String
Dim Address As String
Dim lLen
Dim strMyDomain
Dim internal As Long
Dim external As Long
Const PR_SMTP_ADDRESS As String = "http://schemas.microsoft.com/mapi/proptag/0x39FE001E"
' non-exchange
' userAddress = Session.CurrentUser.Address
' use for exchange accounts
userAddress = Session.CurrentUser.AddressEntry.GetExchangeUser.PrimarySmtpAddress
lLen = Len(userAddress) - InStrRev(userAddress, "#")
strMyDomain = Right(userAddress, lLen)
Set recips = Item.Recipients
For Each recip In recips
Set pa = recip.propertyAccessor
Address = LCase(pa.GetProperty(PR_SMTP_ADDRESS))
lLen = Len(Address) - InStrRev(Address, "#")
str1 = Right(Address, lLen)
If str1 = strMyDomain Then internal = 0
If str1 <> strMyDomain Then external = 1
Next
If internal + external = 1 Then
prompt = "This email is being sent to an External Address. Do you still wish to send?"
If MsgBox(prompt, vbYesNo + vbExclamation + vbMsgBoxSetForeground, "Check Address") = vbNo Then
Cancel = True
End If
End If
End Sub
'''

Answer 1

Set recips = Item.Recipients
For Each recip In recips
Set pa = recip.propertyAccessor
Address = LCase(pa.GetProperty(PR_SMTP_ADDRESS))
lLen = Len(Address) - InStrRev(Address, "#")
str1 = Right(Address, lLen)
dim firstexternaldomain as string
If str1 = strMyDomain Then internal = 0
If str1 <> strMyDomain Then
if len(firstexternaldomain)=0 then
firstexternaldomain = str1
else
if str1 = firstexternaldomain then internal = 0 else external = 1
end if
End if
Next
there could be some less complicated parts in your code, but if it works never change it!
I hope my suggestion works,
Max