發生5.7.1錯誤可能是由於Exchange的System Manager中的SMTP虛擬服務器的設置中沒有選中“allow computers which successfully authenticate to relay”複選框。如下所示,
先打開SMTP Virtual Server的屬性頁的Access頁:
然後點擊“Relay”按鈕,察看“Allow all computers which successfully authenticate to relay,regardless of the list above”是否選中: