Now I know it is not appropriate to be called as Outbox Symptom.It is Sent Items Symptom. 称之为发件箱症状其实也不准确,应该叫已发送邮件症状。
The Store driver on the Hub Transport server also adds messages from the Outbox of a sender on the Mailbox server to the transport pipeline. 集线器传输服务器上的存储驱动器还将邮箱服务器上发件人的发件箱中的邮件添加到传输管道。