RE: SMTP Outgoing - Connection Dropped

Hello Brett,

Thank you for posting in the SBS newsgroup.

According to your description, I understand that you cannot send email to
certain domain names and received the error message "The connection was
dropped by the remote host". If I have misunderstood your concern, please
don't hesitate to let me know.

I appreciate you have done some troubleshoot for this issue and shared
these log files.

To narrow down this issue, please answer and perform the following
questions and steps:

1. I have checked the Server log file, telnet process, there are no
problem. Then checked the result of the SMTP diag, find this:

Checking TCP/UDP SOA serial number using DNS server [139.130.4.4].
TCP test failed.
UDP test succeeded.
Serial number: 2005030201

Checking TCP/UDP SOA serial number using DNS server [203.50.2.71].
TCP test failed.
UDP test succeeded.
Serial number: 2005030201

Two TCP test failed. The SMTP diag tool check the MX, A record of the
internal and remote domain, no problem.

Based on my research, if the Telnet to the destination domain works, but
cannot send email to the certain problematic domain names, it is most
likely a DNS issue. Since this issue only occurs with certain domain names,
so the reason maybe is: some of mail servers in the Internet will perform a
reverse lookup when a SMTP connection is established. If the mail server
does not get the correct info from the reverse lookup, it will drop the
connection. So please contact your ISP to check the DNS records for your
domain to make sure that your Exchange server has a correct reverse DNS
record (PTR record).

2. If this issue is that they can't send email to some domains and the
NDR is as follows:
#5.5.0 smtp;571 from IP Address We do not relay

a. Check if it's actually the remote mail server denies the queuing
request? If so, one should get a Smart Host or get the remote Mail server
exclude their IP from the black list.

b. There're some cases that the outgoing SMTP traffic goes to a different
server instead of the one defined. This kind of issue may be caused by the
name resolution. When the SBS server delivers the outgoing messages through
smarthost, the server queries the MX record of the FQDN of the smarthost
address. If the MX record of the Smart Host is different from the A record,
this will occur, Suggestion is to use the IP address as the smarthost
address.

ISPs so far are:
BellSouth (dsl)
DirectWay (satellite)
Roges/Yahoo (dsl)

3. Please follow the KB 285863 to create a testing SMTP connector to by
Bypass DNS Name Resolution to Test SMTP Mail Flow to Remote Domains:

A. Open Exchange System Manage.
B. Create a SMTP connector.
C. Open the SMTP connector properties, click the General tab, and then
type the IP address of the SMTP server that you cannot send to.
Note: Format the address so that it is enclosed in brackets, for example
"[157.60.112.123]".
D. Adjust the cost so that messages will go through this connector.
E. Click Address Space, add SMTP address Company2.com at this window.
F. Stop the Microsoft Exchange Server Routing Engine Service and the SMTP
service.
G. Restart both services.
H. Send test messages to the problematic domain.
I. Can you send the messages now?

For the detailed information, see the following KB articles:

XCON: How to Bypass DNS Name Resolution to Test SMTP Mail Flow to Remote
Domains
http://support.microsoft.com/?id=285863

HOW TO: Install and Configure SMTP Connectors in Exchange 2000 Server
http://support.microsoft.com/?id=314961

4. Based on my experience, some software can prevent ESMTP commands such
as EHLO. However, Exchange is using ESMTP by default to initiate an ESMTP
conversation with the receiving Mail Server computer. If the commands are
filtered by the software, mail transfer fails and the message will be
logged.

Moreover, if you have ISA server between Exchange and then Internet, please
disable any SMTP filter rules on ISA. If you have Cisco PIX Firewall, you
also need to disable the Mail Guard feature on the Cisco PIX firewall. More
info here:
320027 XCON: Cannot Send or Receive E-Mail Messages Behind a Cisco PIX
Firewall
http://support.microsoft.com/?id=320027

You can also try the following steps to test this issue.

a. Open Exchange System Manager (ESM).
b. Expand to Administrative Groups->first administrative group->Routing
Groups->first routing group->Connectors->SMTP Connector.
c. Right-click SMTP Connector and then click Properties.
d. Click Advanced.
e. Click to select Send "HELO instead of EHLO" and then click OK.
f. Restart all Exchange related services and test this issue again.

5. What's the error message when the user tries to send email to the
certain problematic domain names? Is there any NDR (Non-Delivery Report)?
If yes, I would appreciate your time to forward one of them to me at
v-natliu@xxxxxxxxxxxxxx

6. Please enable SMTP logging and gather SMTP log to troubleshoot the
issue:

A. Open Exchange System Manager, expand Servers -> <Server name> ->
Protocols -> SMTP, right-click "Default SMTP Virtual Server" and click
Properties.

B. Under the General tab, check the option "Enable Logging".

C. With "W3C Extended Log File Format", click "Properties".

D. Under "General Properties", make sure "Use local time for file naming
and rollover" is CHECKED.

E. Switch to the "Extended Properties", and then select to enable All the
logging Options.

F. Click OK to apply the modification.

G. Right-click Default SMTP Virtual Server and click Stop.

H. Right-click Default SMTP Virtual Server and click Start to restart the
SMTP server.

I. Reproduce the issue, repeat step G to stop Default SMTP Virtual Server,
copy out or zip the SMTP log files in the
"%systemroot%\system32\logfiles\SmtpSvc1" folder, and then restart the
"Default SMTP Virtual Server".

7. Please enable message tracking, send an testing email to the certain
problematic domain names and then check the email message under
Tools->Message Tracking Center (you can make a screen capture of the
tracking result and upload the picture here). Regarding how to enable
Message Tracking, please refer to the following MS KB article:

246856 XADM: How to Enable Message Tracking in Exchange 2000 Server
http://support.microsoft.com/?id=246856

I am appreciated your time and cooperation. If anything is unclear, please
feel free to let me know. I am looking forward to hearing from you.

Best regards,

Nathan Liu (MSFT)
Microsoft CSS Online Newsgroup Support

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--------------------
>Thread-Topic: SMTP Outgoing - Connection Dropped
>thread-index: AcWX/FMExgCq1XCESr+gZAcfzFzdAg==
>X-WBNR-Posting-Host: 203.122.199.124
>From: "=?Utf-8?B?QnJldHQgQnJvdWdoYW0=?=" <Brett
Brougham@xxxxxxxxxxxxxxxxxxxxxxxxx>
>Subject: SMTP Outgoing - Connection Dropped
>Date: Wed, 3 Aug 2005 00:24:03 -0700
>Lines: 354
>Message-ID: <518A52FF-7107-4849-B5D5-CB526BCF0CFD@xxxxxxxxxxxxx>
>MIME-Version: 1.0
>Content-Type: text/plain;
> charset="Utf-8"
>Content-Transfer-Encoding: 7bit
>X-Newsreader: Microsoft CDO for Windows 2000
>Content-Class: urn:content-classes:message
>Importance: normal
>Priority: normal
>X-MimeOLE: Produced By Microsoft MimeOLE V6.00.3790.0
>Newsgroups: microsoft.public.windows.server.sbs
>NNTP-Posting-Host: TK2MSFTNGXA03.phx.gbl 10.40.2.250
>Path: TK2MSFTNGXA01.phx.gbl!TK2MSFTNGXA03.phx.gbl
>Xref: TK2MSFTNGXA01.phx.gbl microsoft.public.windows.server.sbs:141043
>X-Tomcat-NG: microsoft.public.windows.server.sbs
>
>Hi
>
>I have the same problem that was listed by teksysman on the 07/25/2005
"The
>coonection was dropped by the remote host". This only occurs with certain
>domain names and never with others. I can send a successful email using
>Telnet to any of the domains that are giving me grief.
>
>I have directed my ISP to direct everything to do with our domain
>'des.com.au' to our site.
>
>This has been a 6 week battle and I am not winning! Help, Please!
>
>Included below is Server Log of Email through Exchange, then with Telnet,
>and then SMTPDiag. I apologise for the length of this email, but thought
it
>better to include the data.
>
>The Server Log File records the following when sending email from
>brett@xxxxxxxxxx to carolmundy@xxxxxxxxxxxxxxxxxx
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionResponse SMTPSVC1
SLAVE
>- 25 - - 220+secmx1.sa.chariot.net.au+ESMTP+Postfix 0 0 42 0 32 SMTP - - -
-
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionCommand SMTPSVC1 SLAVE
-
>25 EHLO - des.com.au 0 0 4 0 32 SMTP - - - -
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionResponse SMTPSVC1
SLAVE
>- 25 - - 250-secmx1.sa.chariot.net.au 0 0 28 0 63 SMTP - - - -
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionCommand SMTPSVC1 SLAVE
-
>25 MAIL - FROM:<brett@xxxxxxxxxx>+SIZE=1497 0 0 4 0 63 SMTP - - - -
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionResponse SMTPSVC1
SLAVE
>- 25 - - 250+Ok 0 0 6 0 110 SMTP - - - -
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionCommand SMTPSVC1 SLAVE
-
>25 RCPT - TO:<carolmundy@xxxxxxxxxxxxxxxxxx> 0 0 4 0 110 SMTP - - - -
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionResponse SMTPSVC1
SLAVE
>- 25 - - 250+Ok 0 0 6 0 500 SMTP - - - -
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionCommand SMTPSVC1 SLAVE
-
>25 DATA - - 0 0 4 0 500 SMTP - - - -
>2005-08-02 20:30:53 203.87.93.130 OutboundConnectionResponse SMTPSVC1
SLAVE
>- 25 - - 354+End+data+with+<CR><LF>.<CR><LF> 0 0 35 0 532 SMTP - - - -
>
>The following works from the command prompt on the server.
>TELNET secmx1.vic.chariot.net.au 25
>220 secmx1.vic.chariot.net.au ESMTP Postfix
>EHLO des.com.au
>250-secmx1.vic.chariot.net.au
>250-PIPELINING
>250-SIZE 18000000
>250-ETRN
>250 8BITMIME
>MAIL FROM:brett@xxxxxxxxxx
>250 Ok
>RCPT TO:carolmundy@xxxxxxxxxxxxxxxxxx
>250 Ok
>DATA
>354 End data with <CR><LF>.<CR><LF>
>Subject: Test
>
>Oh for a glass of scotch!
>.
>250 Ok: queued as 6E9AF3D2450
>QUIT
>221 Bye
>Connection to host lost.
>C:\>
>
>SMTPDiag shows the following...
>
>C:\>cd \clientapps\smtpdiag
>
>C:\ClientApps\SmtpDiag>smtpdiag brett@xxxxxxxxxxx
>carolmundy@xxxxxxxxxxxxxxxxxx
>/v
>
>Searching for Exchange external DNS settings.
>Computer name is SLAVE.
>VSI 1 has the following external DNS servers:
>139.130.4.4,203.50.2.71
>
>Checking SOA for dessminibus.com.au.
>Checking external DNS servers.
>
>Checking TCP/UDP SOA serial number using DNS server [139.130.4.4].
>TCP test failed.
>UDP test succeeded.
>Serial number: 2005030201
>
>Checking TCP/UDP SOA serial number using DNS server [203.50.2.71].
>TCP test failed.
>UDP test succeeded.
>Serial number: 2005030201
>Checking internal DNS servers.
>
>Checking TCP/UDP SOA serial number using DNS server [192.168.1.45].
>TCP test succeeded.
>UDP test succeeded.
>Serial number: 2005030201
>SOA serial number match: Passed.
>
>Checking local domain records.
>Starting TCP and UDP DNS queries for the local domain. This test will try
to
>validate that DNS is set up correctly for inbound mail. This test can fail
for
>3 reasons.
> 1) Local domain is not set up in DNS. Inbound mail cannot be routed to
>local mailboxes.
> 2) Firewall blocks TCP/UDP DNS queries. This will not affect inbound
mail,
>but will affect outbound mail.
> 3) Internal DNS is unaware of external DNS settings. This is a valid
>configuration for certain topologies.
>Checking MX records using TCP: dess.com.au.
> MX: mail.webclick.com.au (10)
>Checking MX records using UDP: dess.com.au.
> MX: mail.webclick.com.au (10)
> A: mail.webclick.com.au [203.217.15.3]
>Both TCP and UDP queries succeeded. Local DNS test passed.
>
>Checking remote domain records.
>Starting TCP and UDP DNS queries for the remote domain. This test will try
to
>validate that DNS is set up correctly for outbound mail. This test can
fail
>for
>3 reasons.
> 1) Firewall blocks TCP/UDP queries which will block outbound mail.
Windows
>2000/NT Server requires TCP DNS queries. Windows Server 2003 will use UDP
>queries first, then fall back to TCP queries.
> 2) Internal DNS does not know how to query external domains. You must
>either use an external DNS server or configure DNS server to query external
>domains.
> 3) Remote domain does not exist. Failure is expected.
>Checking MX records using TCP: dessminibus.com.au.
> MX: mail.dessminibus.com.au (10)
> MX: secmx.sa.chariot.net.au (20)
> MX: secmx.vic.chariot.net.au (30)
> A: secmx.sa.chariot.net.au [203.87.93.132]
> A: secmx.sa.chariot.net.au [203.87.93.130]
> A: secmx.sa.chariot.net.au [203.87.93.131]
> A: secmx.vic.chariot.net.au [203.87.5.165]
> A: secmx.vic.chariot.net.au [203.87.5.164]
> A: mail.dessminibus.com.au [203.87.94.242]
>Checking MX records using UDP: dessminibus.com.au.
> MX: mail.dessminibus.com.au (10)
> MX: secmx.sa.chariot.net.au (20)
> MX: secmx.vic.chariot.net.au (30)
>Both TCP and UDP queries succeeded. Remote DNS test passed.
>
>Checking MX servers listed for carolmundy@xxxxxxxxxxxxxxxxxxx
>Connecting to mail.dessminibus.com.au [203.87.94.242] on port 25.
>Received:
>220 apollo.picknowl.com.au ESMTP Postfix
>
>Sent:
>ehlo dess.com.au
>
>Received:
>250-apollo.picknowl.com.au
>250-PIPELINING
>250-SIZE 20480000
>250-VRFY
>250-ETRN
>250 8BITMIME
>
>
>Sent:
>mail from: <brett@xxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>rcpt to: <carolmundy@xxxxxxxxxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>quit
>
>Received:
>221 Bye
>
>Successfully connected to mail.dessminibus.com.au.
>Connecting to secmx.sa.chariot.net.au [203.87.93.131] on port 25.
>Received:
>220 secmx2.sa.chariot.net.au ESMTP Postfix
>
>Sent:
>ehlo dess.com.au
>
>Received:
>250-secmx2.sa.chariot.net.au
>250-PIPELINING
>250-SIZE 18000000
>250-ETRN
>250 8BITMIME
>
>
>Sent:
>mail from: <brett@xxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>rcpt to: <carolmundy@xxxxxxxxxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>quit
>
>Received:
>221 Bye
>
>Successfully connected to secmx.sa.chariot.net.au.
>Connecting to secmx.sa.chariot.net.au [203.87.93.130] on port 25.
>Received:
>220 secmx1.sa.chariot.net.au ESMTP Postfix
>
>Sent:
>ehlo dess.com.au
>
>Received:
>250-secmx1.sa.chariot.net.au
>250-PIPELINING
>250-SIZE 18000000
>250-ETRN
>250 8BITMIME
>
>
>Sent:
>mail from: <brett@xxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>rcpt to: <carolmundy@xxxxxxxxxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>quit
>
>Received:
>221 Bye
>
>Successfully connected to secmx.sa.chariot.net.au.
>Connecting to secmx.sa.chariot.net.au [203.87.93.132] on port 25.
>Received:
>220 secmx3.sa.chariot.net.au ESMTP Postfix
>
>Sent:
>ehlo dess.com.au
>
>Received:
>250-secmx3.sa.chariot.net.au
>250-PIPELINING
>250-SIZE 18000000
>250-ETRN
>250 8BITMIME
>
>
>Sent:
>mail from: <brett@xxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>rcpt to: <carolmundy@xxxxxxxxxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>quit
>
>Received:
>221 Bye
>
>Successfully connected to secmx.sa.chariot.net.au.
>Connecting to secmx.vic.chariot.net.au [203.87.5.164] on port 25.
>Received:
>220 secmx1.vic.chariot.net.au ESMTP Postfix
>
>Sent:
>ehlo dess.com.au
>
>Received:
>250-secmx1.vic.chariot.net.au
>250-PIPELINING
>250-SIZE 18000000
>250-ETRN
>250 8BITMIME
>
>
>Sent:
>mail from: <brett@xxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>rcpt to: <carolmundy@xxxxxxxxxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>quit
>
>Received:
>221 Bye
>
>Successfully connected to secmx.vic.chariot.net.au.
>Connecting to secmx.vic.chariot.net.au [203.87.5.165] on port 25.
>Received:
>220 secmx2.vic.chariot.net.au ESMTP Postfix
>
>Sent:
>ehlo dess.com.au
>
>Received:
>250-secmx2.vic.chariot.net.au
>250-PIPELINING
>250-SIZE 18000000
>250-ETRN
>250 8BITMIME
>
>
>Sent:
>mail from: <brett@xxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>rcpt to: <carolmundy@xxxxxxxxxxxxxxxxxx>
>
>Received:
>250 Ok
>
>Sent:
>quit
>
>Received:
>221 Bye
>
>Successfully connected to secmx.vic.chariot.net.au.
>
>C:\ClientApps\SmtpDiag>
>
>
>
>>From Brett
>
>
>

.

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