Exchange server 2007 451 error messages ONLY for aol, aim and comcast.

We recently had a new ISP install a new internet line so we got a new WAN ip and info from them as well as a new firewall that they manage. Ever since we changed over on Wednesday we get error 451's when trying to send out to aol, aim and comcast. Why? Nothing has changed on our end and they control the firewall side.

Any help would be great.
jmahlmannAsked:
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jmahlmannConnect With a Mentor Author Commented:
It was as I thought. The new ISP had to put the ptr on their servers. It had nothing to do with us.
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WORKS2011Austin Tech CompanyCommented:
you may try this link for comcast problems
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Elmar KoschkaIT System EngineerCommented:
It sounds you have your dns settings not configured for new wan ip?
Please check DNS IP and PTR Records for your Exchange Server
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PadamdeepCommented:
Could you post the NDR here?

~ Singh
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jmahlmannAuthor Commented:
I checked and everything is pointing to the correct new dns ip. I even added an spf record.
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suriyaehnopCommented:
Please post the NDR
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jmahlmannAuthor Commented:
Could this be a firewall issue or dns issue with the new ISP? There is nothing different about our server and it was working fine before the change? The ISP controls the firewall. What can we look for?
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PadamdeepCommented:
Could you post NDR?

~ Singh
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jmahlmannAuthor Commented:
comcast.net      DnsConnectorDelivery      Retry      3      Monday, April 02, 2012 10:44:25 AM      451 4.4.0 Primary target IP address responded with: "554 imta24.westchester.pa.mail.comcast.net comcast 64.19.138.115 Comcast requires that all mail servers must have a PTR record with a valid Reverse DNS entry. Currently your mail server does not fill that requirement. For more information, refer to: http://postmaster.comcast.net/smtp-error-codes.php#554." Attempted failover to alternate host, but that did not succeed. Either there are no alternate hosts, or delivery failed to all alternate hosts.

The ISP has added this to their servers. We shall see if that works.
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PadamdeepCommented:
so they are clearly talking about PTR record not found.

Do you know your External IP address or addresses which is seen by external domains?

If you are not sure about it then send an email to Domain who is able to receive emails from you and check email header. That will tell you your external IP seen by Remote Domains.

Once you find yor External IP address, look for PTR record OR post your IP here and I can do it for you.

~ Singh
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jmahlmannAuthor Commented:
Where do you do it? What am I missing?

Thanks.
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PadamdeepCommented:
ok. In order to answer your question. I need to ask you one.

Do you send emails to other Domain through a SMART Host or you use DNS to send emails directly from your Exchange Server to remote domains?

~ Singh
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jmahlmannAuthor Commented:
dns
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PadamdeepCommented:
Ok..

1. Open the command prompt on Exchange Server which sends out email to Internet.
2. Type Telnet maila.microsoft.com 25
3. Type Helo abc.com


Perform the above steps here and copy/paste everything from cmd prompt here.

~ Singh
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jmahlmannAuthor Commented:
It's going back to my ip. Is there a private way to send the ip?
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PadamdeepCommented:
ok..You don't have to share the IP address with me.

Go to the following website.

http://www.mxtoolbox.com/ReverseLookup.aspx

Type the IP address that you have got from command prompt and see if it resolves to a Name/FQDN.

~ Singh
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jmahlmannAuthor Commented:
This is what I get:
(ipaddress).in-addr.arpa:ptr -monmouth.com: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond
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PadamdeepCommented:
Since you know your outgoing up now, please check with your ISP to find out if it has a valid ptr or not. If you have multiple outgoing up then all those should be having valid ptr.

Singh
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jmahlmannAuthor Commented:
It had to do with the PTR on the ISP side. No one suggested that even thought I said I thought that is what it was. I resolved this last week.
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