有同事反映，客户发过来的邮件他看不到，但是客户却可以接收到他发过去的邮件。所以去查看了当天的SMTP IN的日志：

Tue 2008-03-11 15:09:39: Authenticated as [email=A@M]A@M[/email]   
Tue 2008-03-11 15:09:39: <-- MAIL FROM: <[email=A@M]A@M[/email]>                                <---同事的邮件地址...
Tue 2008-03-11 15:09:39: --> 250 <[email=A@M]A@M[/email]>, Sender ok
Tue 2008-03-11 15:09:39: <-- RCPT TO: <[email=B@N]B@N[/email]>                                    <---客户的邮件地址...
Tue 2008-03-11 15:09:39: --> 250 <[email=B@N][email=B@N]B@N[/email]>Recipient[/email] ok         
Tue 2008-03-11 15:09:39: <-- RSET
Tue 2008-03-11 15:09:39: --> 250 RSET? Well, ok.
Tue 2008-03-11 15:09:39: <-- RSET
Tue 2008-03-11 15:09:39: --> 250 RSET? Well, ok.
Tue 2008-03-11 15:09:40: <-- MAIL FROM: <[email=A@M]A@M[/email]>
Tue 2008-03-11 15:09:40: --> 250 <[email=A@M]A@M[/email]>, Sender ok
Tue 2008-03-11 15:09:40: <-- RCPT TO: <[email=B@N]B@N[/email]>
Tue 2008-03-11 15:09:40: --> 250 <[email=B@N]B@N[/email]>, Recipient ok
Tue 2008-03-11 15:09:40: <-- DATA
Tue 2008-03-11 15:09:40: Creating temp file (SMTP): d:\mdaemon\queues\temp\md50000358011.tmp
Tue 2008-03-11 15:09:40: --> 354 Enter mail, end with <CRLF>.<CRLF>
Tue 2008-03-11 15:09:40: Message size: 27897 bytes
Tue 2008-03-11 15:09:40: Passing message through AntiVirus (Size: 27897)...
Tue 2008-03-11 15:09:40: *  Message is clean (no viruses found)
Tue 2008-03-11 15:09:40: ---- End AntiVirus results
Tue 2008-03-11 15:09:40: Message creation successful: d:\mdaemon\queues\inbound\md50001062752.msg
Tue 2008-03-11 15:09:40: --> 250 Ok, message saved <Message-ID: <[email=013401c88346$deec5a00$8b0aa8c0@M]013401c88346$deec5a00$8b0aa8c0@M[/email]>>
Tue 2008-03-11 15:09:40: <-- QUIT
Tue 2008-03-11 15:09:40: --> 221 See ya in cyberspace
Tue 2008-03-11 15:09:40: SMTP session successful (Bytes in/out: 28100/602)

奇怪了~SMTP IN不是应该都是发进来的邮件的记录吗？怎么我们同事反而变成发送者了（MAIL FROM: <[email=A@M]A@M[/email]>），而客户成了接受者呢（RCPT TO: <[email=B@N]B@N[/email]>）？

这个是正常的，一次ESMTP认证过程，同时也是一个SMTP入站操作，因此也会被记录在此日志中。

呵呵~以前到还真没注意过~仔细看了一下都还是真是这样的...受教了~