最近半个月一直在跟踪一家客户，他们使用的是U-mail系统，大家众所周知U-mail系统是根据Mdaemon系统内核改变而来，因此会将Mdaemon的本来面貌改变的不成样子。很多东西功能实现起来就比较麻烦，因为umail将很多功能封装起来在配置文件，只有Umail的技术工程师知道，不像其他系统很公开。
尤其是U-mail的9.8.1左右版本。更是变态到家，如果你启用了更智能的路由选项，不管是发不通走中继还是全部走中继，umail都会出问题。请听我娓娓道来。
1、发不通走海外邮件中继的话，umail的机制很搞笑，比如遇到IP在国际黑名单他也都是自己发送，而不是第二轮投递经过只能路由服务器。还有连接不上对方的服务器也不会经过第三方邮件中继来发送，特别奇怪
2、如果全部走中继的话，就会自动生成一些延迟报告堵住队列，而且还是22分钟的延迟报告，从而让正常的邮件发不出去特别的奇怪
下面有一段全部走中继的22分钟延迟报告。

PS
— Session Transcript —

Sat 2013-10-12 13:01:18: Parsing message

Sat 2013-10-12 13:01:18: * From: allen.zhong@email-cm.com

Sat 2013-10-12 13:01:18: * To: Sam@bbb.com.vn

Sat 2013-10-12 13:01:18: * Subject: =?utf-8?B?5Zue5aSNOiBSRTogVGVuZ2ZlbmcgMTAvMTAgYWlyIHNoaXBwaW5nIERvYyAgLCBDLyBUQkcsIFMvIFBVVElBTiBURU5GRU5HLCAgWE1OLVNHTiwgUkVBRFkgTk9XIDg1MS0wMjM3MzU4Mg==?=

Sat 2013-10-12 13:01:18: * Size (bytes): 2967952

Sat 2013-10-12 13:01:18: * Message-ID: <2013101212370353185743@email-cm.com>

Sat 2013-10-12 13:01:18: Attempting SMTP connection to [vinafreight.com.vn]

Sat 2013-10-12 13:01:18: Resolving MX records for [bbb.com.vn] (DNS Server: 8.8.8.8)…

Sat 2013-10-12 13:01:18: * P=010 S=000 D=bbb.com.vn TTL=(10) MX=[mail.bbb.com.vn]

Sat 2013-10-12 13:01:18: Attempting SMTP connection to [mail.bbb.com.vn:25]

Sat 2013-10-12 13:01:18: Resolving A record for [mail.bbb.com.vn] (DNS Server: 8.8.8.8)…

Sat 2013-10-12 13:01:18: * D=mail.bbb.com.vn TTL=(40) A=[203.162.48.241]

Sat 2013-10-12 13:01:18: Attempting SMTP connection to [203.162.48.241:25]

Sat 2013-10-12 13:01:18: Waiting for socket connection…

Sat 2013-10-12 13:01:18: * Connection established (10.10.10.11:2201 -> 203.162.48.241:25)

Sat 2013-10-12 13:01:18: Waiting for protocol to start…

Sat 2013-10-12 13:01:18: <-- 220 mail.bbb.com.vn ESMTP MDaemon 13.0.0; Sat, 12 Oct 2013 11:58:43 +0700

Sat 2013-10-12 13:01:18: --> EHLO email-cm.com

Sat 2013-10-12 13:01:18: <-- 250-mail.bbb.com.vn Hello email-cm.com, pleased to meet you

Sat 2013-10-12 13:01:18: <-- 250-ETRN

Sat 2013-10-12 13:01:18: <-- 250-AUTH LOGIN CRAM-MD5 PLAIN

Sat 2013-10-12 13:01:18: <-- 250-8BITMIME

Sat 2013-10-12 13:01:18: <-- 250-STARTTLS

Sat 2013-10-12 13:01:18: <-- 250 SIZE

Sat 2013-10-12 13:01:18: --> MAIL From: SIZE=2967952

Sat 2013-10-12 13:01:18: <-- 250 , Sender ok

Sat 2013-10-12 13:01:18: –> RCPT To:

Sat 2013-10-12 13:01:54: <-- 250 , Recipient ok

Sat 2013-10-12 13:01:54: –> DATA

Sat 2013-10-12 13:01:54: <-- 354 Enter mail, end with .

Sat 2013-10-12 13:01:54: Sending to [203.162.48.241]

Sat 2013-10-12 13:03:19: * Winsock Error 10054 Connection was reset by the other side!

Sat 2013-10-12 13:03:19: Error writing to socket

Sat 2013-10-12 13:03:19: Socket connection closed by the other side (how rude!)

Sat 2013-10-12 13:03:19: * Winsock Error 10053 Connection abort.

Sat 2013-10-12 13:03:19: Connection closed

Sat 2013-10-12 13:03:19: Attempting to send message to smart host

Sat 2013-10-12 13:03:19: Attempting SMTP connection to [relaymail.yi-enter.com:25]

Sat 2013-10-12 13:03:19: Resolving A record for [relaymail.yi-enter.com] (DNS Server: 8.8.8.8)…

Sat 2013-10-12 13:03:19: This message is 23 minutes old; it has 0 minutes left in this queue

Sat 2013-10-12 13:03:19: Remote queue lifetime exceeded; message placed in retry queue

— End Transcript —