更改收件人时，Outlook VBA MailItem_PropertyChange事件将触发三次

Private Sub Application_ItemLoad(ByVal Item As Object)
    If TypeOf Item Is Outlook.MailItem Then
        Set WithEvents MailItem = Item
    End If
End Sub

Private Sub MailItem_PropertyChange(ByVal Name As String)
    If Name = "To" Or Name = "CC" Or Name = "BCC" Then
        Dim recipients As Outlook.Recipients
        Dim recipient As Outlook.Recipient
        Dim recipientType As String
        
        Set recipients = MailItem.Recipients
        
        For Each recipient In recipients
            If recipient.Type = olTo Then
                recipientType = "收件人"
            ElseIf recipient.Type = olCC Then
                recipientType = "抄送"
            ElseIf recipient.Type = olBCC Then
                recipientType = "密送"
            End If
            
            Debug.Print recipientType & "：" & recipient.Name
        Next recipient
    End If
End Sub