451 DNS Query Failed error in Exchange 2007
We are having trouble sending email to one particular domain. This is using Exchange 2007 on a Windows SBS 2008 box. Only server at our site, only problem we have seen with email in 6 months since it was implemented. I am receiving a 451 4.4.0 DNS query failed error when trying to send to the domain polytronix.com . From the Exchange server I can telnet to the client's mail server and receive a HELO. NSLookup gives the following:
C:\Windows\system32>nslookup -type=mx polytronix.com
Server: UnKnown
Address: fe80::23c8:9a82:d40b:251a
Non-authoritative answer:
polytronix.com MX preference = 10, mail exchanger = mail.polytronix.com
polytronix.com MX preference = 20, mail exchanger = mail.polytronix.com
mail.polytronix.com internet address = 72.16.238.22
mail.polytronix.com internet address = 72.16.238.22
I am waiting to hear back from the customer as I am no longer sure the IP from the NSLookup is correct (customer stated the IP was 72.16.238.18, not 22). Anyone have any other ideas on how I can troubleshoot/resolve this issue? Thanks in advance!
October 19th, 2009 5:25pm
Hi,Please try to send the email by using telnet to narrow down the cause.http://support.microsoft.com/kb/153119If you can send the email by using the telnet, this indicates the client's mail server doesn't block your email address. Then you need to create a separate send connector and set the client's mail server as the smarthost to send the email. Through this we can confirm whether the DNS is the cause of the issue. If that is the DNS issue, you need to check the "Use the External DNS Lookup settings on the transport server" option or update the MX record of the particular domain.ThanksAllen
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October 21st, 2009 11:37am
OK I did confirm with the customer (Polytronix.com) that the IP in the NSLookup was correct so I can rule that out now. Here is the results of my telnet with their mail server at mail.polytronix.com. Not sure if I did this right because the tutorial was very ambiguous - was I supposed to send the email to myself or to the customer @ Polytronix? In either case it took me a while to get this to go through - every other session instead of returning 250 for these commands it would give me a bevy of other error messages (things like bad command, unknown address, and my session was killed a few times by a lost connection from their server).
220 beta.Polytronix.com Microsoft ESMTP MAIL Service ready at Wed, 21 Oct 2009 0
8:28:51 -0500
EHLO
250-beta.Polytronix.com Hello [67.52.2.58]
250-SIZE
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-X-ANONYMOUSTLS
250-AUTH NTLM
250-X-EXPS GSSAPI NTLM
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250-XEXCH50
250 XRDST
MAIL FROM:amartin@tg3electronics.com
250 2.1.0 Sender OK
RCPT TO:lshedenhelm@polytronix.com
500 5.3.3 Unrecognized command
RCPT TO:lshedenhelm@polytronix.com
250 2.1.5 Recipient OK
DATA
354 Start mail input; end with <CRLF>.<CRLF>
Subject:test message via telnet
This is a test message sent via mail.polytronix.com over telnet to help troubles
hoot TG3 Electronics email problem with Polytronix.
.
250 2.6.0 <86d32082-944a-4647-8ccf-48982fb35226@beta.Polytronix.com> Queued mail
for delivery
quit
221 2.0.0 Service closing transmission channel
I will look for instructions on the proper way to create the send connector you are talking about, but if you have details on how to do that it would help greatly. Thanks!
October 21st, 2009 4:41pm
Hi,Yes, you need to send the email to the customer@ploytronix.com from your email address. From the information, it seems that you can send the email without no issue. This indicates the remote server is openning for your email address.The possible cause is the DNS issue. Now please check the "Use the External DNS Lookup settings on the transport server" optionon the current Send Connector to examine whether you can send the email normally.ThanksAllen
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October 22nd, 2009 1:22pm
Thanks that works! Would not have found that setting on my own.
October 22nd, 2009 5:42pm
Hi,Glad to hear that is working.ThanksAllen
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October 23rd, 2009 5:49am