Você pode interromper a resposta de maneira similar à nesta questão
Insira um novo módulo como este e, em seguida, no ThisOutlookSession
module cole o código abaixo
Dim WithEvents insp As Outlook.Inspectors
Dim WithEvents mailItem As Outlook.MailItem
' This is called on Outlook startup
Private Sub Application_Startup()
Set insp = Application.Inspectors
End Sub
' This is called when a new Inspector is created.
Private Sub insp_NewInspector(ByVal Inspector As Inspector)
If Inspector.CurrentItem.Class = olMail Then
Set mailItem = Inspector.CurrentItem
End If
End Sub
' Called when you press Reply
Private Sub mailItem_Reply(ByVal Response As Object, Cancel As Boolean)
Dim msg As String
Dim result As Integer
If myMailItem.Recipients.count > 1 Then
msg = "Do you really want to reply to one?"
result = MsgBox(msg, vbYesNo, "Reply Check")
If result = vbNo Then
Cancel = True
End If
End If
End Sub