Question : Problems with SMTP connections dropping

Hi,

We are experiencing problems with SMTP connections between to a specific domain. The MX record for the Y domain points to an SMTP gateway at the X domain. The X domain SMTP gateway is MDaemon Server 10.0.5. The SMTP server for the Y domain is Microsoft Exchange 2007 (SP1 with Rollup 7). The problem is that the Y domain is dropping connections almost exactly 60 seconds after the email is sent. See the enclosed SMTP log from the X domain:

Tue 2009-05-12 15:08:29: Session 376; child 29
Tue 2009-05-12 15:07:28: Parsing message pd50004600261.msg>
Tue 2009-05-12 15:07:28: *  From: [email protected]
Tue 2009-05-12 15:07:28: *  To: [email protected]
Tue 2009-05-12 15:07:28: *  Subject: Subject Line
Tue 2009-05-12 15:07:28: *  Size (bytes): 6166
Tue 2009-05-12 15:07:28: *  Message-ID: <22740960.1242140802090.JavaMail.WIN-DOSY30F3GIR$@WIN-DOSY30F3GIR>
Tue 2009-05-12 15:07:28: *  Route slip host: mail.yyyyyyyy.yy
Tue 2009-05-12 15:07:28: *  Route slip port: 25
Tue 2009-05-12 15:07:28: Attempting SMTP connection to [mail.yyyyyyyy.yy]
Tue 2009-05-12 15:07:28: Resolving MX records for [mail.yyyyyyyy.yy] (DNS Server: 172.31.0.102)...
Tue 2009-05-12 15:07:28: *  Name server has no valid records of the requested type for that domain
Tue 2009-05-12 15:07:28: Attempting SMTP connection to [mail.yyyyyyyy.yy:25]
Tue 2009-05-12 15:07:28: Resolving A record for [mail.yyyyyyyy.yy] (DNS Server: 172.31.0.102)...
Tue 2009-05-12 15:07:28: *  D=mail.yyyyyyyy.yy TTL=(40) A=[y.y.y.y]
Tue 2009-05-12 15:07:28: Attempting SMTP connection to [y.y.y.y:25]
Tue 2009-05-12 15:07:28: Waiting for socket connection...
Tue 2009-05-12 15:07:28: *  Connection established (172.31.0.104:3323 -> y.y.y.y:25)
Tue 2009-05-12 15:07:28: Waiting for protocol to start...
Tue 2009-05-12 15:07:28: <-- 220 mail.yyyyyyyy.yy Microsoft ESMTP MAIL Service ready at Tue, 12 May 2009 15:05:45 +0200
Tue 2009-05-12 15:07:28: --> EHLO xxxxxxx.xx
Tue 2009-05-12 15:07:28: <-- 250-mail.yyyyyyyy.yy Hello [x.x.x.x]
Tue 2009-05-12 15:07:28: <-- 250-SIZE 25845760
Tue 2009-05-12 15:07:28: <-- 250-DSN
Tue 2009-05-12 15:07:28: <-- 250-ENHANCEDSTATUSCODES
Tue 2009-05-12 15:07:28: <-- 250-AUTH
Tue 2009-05-12 15:07:28: <-- 250-8BITMIME
Tue 2009-05-12 15:07:28: <-- 250-BINARYMIME
Tue 2009-05-12 15:07:28: <-- 250 CHUNKING
Tue 2009-05-12 15:07:28: --> MAIL From: SIZE=6166
Tue 2009-05-12 15:07:28: <-- 250 2.1.0 Sender OK
Tue 2009-05-12 15:07:28: --> RCPT To:
Tue 2009-05-12 15:07:28: <-- 250 2.1.5 Recipient OK
Tue 2009-05-12 15:07:28: --> DATA
Tue 2009-05-12 15:07:28: <-- 354 Start mail input; end with .
Tue 2009-05-12 15:07:28: Sending pd50004600261.msg> to [y.y.y.y]
Tue 2009-05-12 15:07:28: Transfer Complete

****** This is where a normal session should end:

Tue 2009-05-12 15:08:29: <-- 250 2.6.0 575B4.0042C6B7-C12575B4.004390[email protected]z> Queued mail for delivery
Tue 2009-05-12 15:08:29: --> QUIT
Tue 2009-05-12 15:08:29: <-- 221 2.0.0 Service closing transmission channel
Tue 2009-05-12 15:08:29: SMTP session successful (Bytes in/out: 513/4969365)

****** But this is how the session actually ends:

Tue 2009-05-12 15:08:29: Socket connection closed by the other side (how rude!)
Tue 2009-05-12 15:08:29: This message is 1 minutes old; it has 59 minutes left in this queue
Tue 2009-05-12 15:08:29: SMTP session terminated (Bytes in/out: 333/6267)

As you can see, the Microsoft Exchange Server 2007 SMTP ends the session by closing the connection. I've seen in some logs that it says "Bad sequence of commands" but now I don't see that even anymore. The SMTP log on the Y domain (Exchange) looks like this for the same message:

2009-05-12T13:06:54.575Z,EXCHANGESERVER\Default,08CBA1139A506B17,0,192.168.254.12:25,x.x.x.x:52371,+,,
2009-05-12T13:06:54.575Z,EXCHANGESERVER\Default,08CBA1139A506B17,1,192.168.254.12:25,x.x.x.x:52371,*,SMTPSubmit SMTPAcceptAnySender SMTPAcceptAuthoritativeDomainSender AcceptRoutingHeaders,Set Session Permissions
2009-05-12T13:06:54.575Z,EXCHANGESERVER\Default,08CBA1139A506B17,2,192.168.254.12:25,x.x.x.x:52371,>,"220 mail.yyyyyyyy.yy Microsoft ESMTP MAIL Service ready at Tue, 12 May 2009 15:06:53 +0200",
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,3,192.168.254.12:25,x.x.x.x:52371,<,EHLO xxxxxxx.xx,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,4,192.168.254.12:25,x.x.x.x:52371,>,250-mail.yyyyyyyy.yy Hello [x.x.x.x],
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,5,192.168.254.12:25,x.x.x.x:52371,>,250-SIZE 25845760,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,6,192.168.254.12:25,x.x.x.x:52371,>,250-PIPELINING,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,7,192.168.254.12:25,x.x.x.x:52371,>,250-DSN,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,8,192.168.254.12:25,x.x.x.x:52371,>,250-ENHANCEDSTATUSCODES,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,9,192.168.254.12:25,x.x.x.x:52371,>,250-STARTTLS,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,10,192.168.254.12:25,x.x.x.x:52371,>,250-AUTH,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,11,192.168.254.12:25,x.x.x.x:52371,>,250-8BITMIME,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,12,192.168.254.12:25,x.x.x.x:52371,>,250-BINARYMIME,
2009-05-12T13:06:54.637Z,EXCHANGESERVER\Default,08CBA1139A506B17,13,192.168.254.12:25,x.x.x.x:52371,>,250 CHUNKING,
2009-05-12T13:06:54.669Z,EXCHANGESERVER\Default,08CBA1139A506B17,14,192.168.254.12:25,x.x.x.x:52371,<,MAIL From: SIZE=6166,
2009-05-12T13:06:54.669Z,EXCHANGESERVER\Default,08CBA1139A506B17,15,192.168.254.12:25,x.x.x.x:52371,*,08CBA1139A506B17;2009-05-12T13:06:54.575Z;1,receiving message
2009-05-12T13:06:54.669Z,EXCHANGESERVER\Default,08CBA1139A506B17,16,192.168.254.12:25,x.x.x.x:52371,>,250 2.1.0 Sender OK,
2009-05-12T13:06:54.700Z,EXCHANGESERVER\Default,08CBA1139A506B17,17,192.168.254.12:25,x.x.x.x:52371,<,RCPT To:,
2009-05-12T13:06:54.700Z,EXCHANGESERVER\Default,08CBA1139A506B17,18,192.168.254.12:25,x.x.x.x:52371,>,250 2.1.5 Recipient OK,
2009-05-12T13:06:54.731Z,EXCHANGESERVER\Default,08CBA1139A506B17,19,192.168.254.12:25,x.x.x.x:52371,<,DATA,
2009-05-12T13:06:54.731Z,EXCHANGESERVER\Default,08CBA1139A506B17,20,192.168.254.12:25,x.x.x.x:52371,>,354 Start mail input; end with .,
2009-05-12T13:07:56.969Z,EXCHANGESERVER\Default,08CBA1139A506B17,21,192.168.254.12:25,x.x.x.x:52371,-,,Remote

As far as I can read these logs, the SMTP serve at the Y domain (Exchange) awaits the . but seems like it for some reason never gets it. After one minute, according to both SMTP logs then session is ended. Has anyone experienced anything like this? Does anyone interpret the logs differently than me?

All mail going to the Y domain gets the same treatment by the Y SMTP, when sent from the X domain. When I try from the server that runs the X domain SMTP server by using telnet to port 25 at the Y domain, it lets me send email without any trouble.

Regards,

Tomas Andersson

Answer : Problems with SMTP connections dropping

Just to add to the confusion. I re-enabled ESMTP for the MDaemon server because other SMTP clients (MS Outlook) started having problems sending emails. Now both the regular SMTP clients and email to the Y domain works like a charm. Maybe it's time to start doing something else, like driving a garbage truck instead? ;-)