看起來有人在使用我的電子郵件伺服器發送垃圾郵件。我能做些什麼來保護它？

在過去的兩天裡，我在收件箱中看到了一些神秘的電子郵件“退回”通知。下面粘貼的是其中之一的原始內容。請注意，我已經審查了我自己的個人資訊。所有這些郵件的to地址都是 kunnu@mydomain.com。

有問題的伺服器是一個執行 Apache、Caucho、Resin 和其他幾個與電子郵件無關的程序的 Ubuntu 9.10 機器。據我所知，它沒有安裝後綴（which postfix什麼都不返回）。

我可以採取哪些步驟來正確診斷和解決問題？

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垃圾郵件發送者的正常做法是使用其他人的電子郵件地址作為發件人。這些地址的收集方式與目標地址相同。除了驗證消息不是真正從您的系統發送的之外，您無能為力。

如果消息是從您的系統發送的，那麼您需要找出是誰或什麼在發送消息並採取適當的措施。

如果消息正在通過您的系統中繼，請確保立即禁用中繼。

引用自：https://serverfault.com/questions/266816