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SMTP Connectors not delivering mail

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SMTP Connectors not delivering mail - 1.Nov.2006 4:38:41 PM

Ct_Net_Admin1972

Posts: 16
Joined: 10.Apr.2006
Status: offline

My company stop using our ISP as our relay and we are now relaying through our mail server. I have noticed serveral SMTP connectors being created throught out the day that are filling up with mail and not being delivered. These connectors include hotmail.com, msn.com, masonline.com etc.. If I force the connection some do evetually disappear but the hotmail.com is still filling up with email. Im not sure if email is even being delivered at all to these domains. I did get a few NDR emails with an error of

there was a SMTP communication problem with the recipient's email server. Please contact your system administrator.
<chnmail.chnct.org #5.5.0 smtp;501 Bad Input>

I ran smtpdiag with few of the email address in these domains from email address in our domain : Below are the results these tests:

any suggestions would be great !
thanks

C:\>smtpdiag smauro@chnct.org tward@flagshipnetworks.com

Searching for Exchange external DNS settings.
Computer name is CHN01528.

Checking SOA for flagshipnetworks.com.
Checking external DNS servers.
Checking internal DNS servers.
SOA serial number match: Passed.

Checking local domain records.
Checking MX records using TCP: chnct.org.
Checking MX records using UDP: chnct.org.
Both TCP and UDP queries succeeded. Local DNS test passed.

Checking remote domain records.
Checking MX records using TCP: flagshipnetworks.com.
Checking MX records using UDP: flagshipnetworks.com.
Both TCP and UDP queries succeeded. Remote DNS test passed.

Checking MX servers listed for tward@flagshipnetworks.com.
Connecting to mail.flagshipnetworks.com [208.41.56.20] on port 25.
Successfully connected to mail.flagshipnetworks.com.
Connecting to mx01-dom.earthlink.net [207.217.125.17] on port 25.
Error: Expected "250". Server rejected the recipient address.
Failed to submit mail to mx01-dom.earthlink.net.
Connecting to mx00-dom.earthlink.net [207.217.125.16] on port 25.
Error: Expected "250". Server rejected the recipient address.
Failed to submit mail to mx00-dom.earthlink.net.

C:\>smtpdiag jcharette@chnct.org tward@flagshipnetworks.com

Searching for Exchange external DNS settings.
Computer name is CHN01528.

Checking SOA for flagshipnetworks.com.
Checking external DNS servers.
Checking internal DNS servers.
SOA serial number match: Passed.

Checking local domain records.
Checking MX records using TCP: chnct.org.
Checking MX records using UDP: chnct.org.
Both TCP and UDP queries succeeded. Local DNS test passed.

Checking remote domain records.
Checking MX records using TCP: flagshipnetworks.com.
Checking MX records using UDP: flagshipnetworks.com.
Both TCP and UDP queries succeeded. Remote DNS test passed.

Checking MX servers listed for tward@flagshipnetworks.com.
Connecting to mail.flagshipnetworks.com [208.41.56.20] on port 25.
Successfully connected to mail.flagshipnetworks.com.
Connecting to mx01-dom.earthlink.net [207.217.125.17] on port 25.
Error: Expected "250". Server rejected the recipient address.
Failed to submit mail to mx01-dom.earthlink.net.
Connecting to mx00-dom.earthlink.net [207.217.125.16] on port 25.
Error: Expected "220". Server is not accepting connections.
Failed to submit mail to mx00-dom.earthlink.net.

C:\>smtpdiag smauro@chnct.org cnewman31@hotmail.com

Searching for Exchange external DNS settings.
Computer name is CHN01528.

Checking SOA for hotmail.com.
Checking external DNS servers.
Checking internal DNS servers.
SOA serial number match: Passed.

Checking local domain records.
Checking MX records using TCP: chnct.org.
Checking MX records using UDP: chnct.org.
Both TCP and UDP queries succeeded. Local DNS test passed.

Checking remote domain records.
Checking MX records using TCP: hotmail.com.
Checking MX records using UDP: hotmail.com.
Both TCP and UDP queries succeeded. Remote DNS test passed.

Checking MX servers listed for cnewman31@hotmail.com.
Connecting to mx2.hotmail.com [65.54.245.40] on port 25.
Error: Expected "250". Server rejected the recipient address.
Failed to submit mail to mx2.hotmail.com.
Connecting to mx2.hotmail.com [65.54.190.50] on port 25.
Error: Expected "220". Server is not accepting connections.
Failed to submit mail to mx2.hotmail.com.
Connecting to mx2.hotmail.com [65.54.244.40] on port 25.
Error: Expected "250". Server rejected the recipient address.
Failed to submit mail to mx2.hotmail.com.
Connecting to mx1.hotmail.com [65.54.245.8] on port 25.
Error: Expected "220". Server is not accepting connections.
Failed to submit mail to mx1.hotmail.com.
Connecting to mx1.hotmail.com [64.4.50.50] on port 25

Post #: 1

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RE: SMTP Connectors not delivering mail - 1.Nov.2006 4:59:24 PM

jchong

Posts: 2516
Joined: 1.Dec.2005
From: Centreville, Virginia
Status: offline

Do you have a reverse dns record?

_____________________________

James Chong
MCSE | M+, S+, MCTS, Security+
msexchangetips.blogspot.com

(in reply to Ct_Net_Admin1972)

Post #: 2

RE: SMTP Connectors not delivering mail - 2.Nov.2006 11:30:39 AM

AdminFix

Posts: 62
Joined: 13.Mar.2006
Status: offline

Looks to me like you might be blacklisted on the internet. Please check your outbound IP address for SMTP connection with IP Blacklist scanner @ www.dnsstuff.com.

It is the first one in the middle column. If listed, follow the link given by the test to delist your IP from DNS RBL.

PS: Hotmail doesn't need Reverse Lookup Record, but it does scan your connecting IP against a list of DNS RBL.

< Message edited by AdminFix -- 2.Nov.2006 11:31:52 AM >

(in reply to jchong)

Post #: 3

RE: SMTP Connectors not delivering mail - 6.Nov.2006 2:57:18 PM

Ct_Net_Admin1972

Posts: 16
Joined: 10.Apr.2006
Status: offline

thanks for your replies.,

Yes we do have a reverse dns record with our ISP created . I checked that this morning by looking on dnsstuff as well as doing an nslookup from my workstation.
I also checked our public ip for being blacklisted and it passed all the tests and is not on any blacklists.

I spoke to an engineer for our ISP and he suggested that we stop using forwarders and start using Root hints instead. he said this is more robust and alot faster.

please let me know your thoughts.

(in reply to AdminFix)

Post #: 4