Destination Server Rejecting Email

I have a client whose email works fine with the exception of any address that he sends to that goes to ???????@comcast.net. Any other user in the company can send it but not him. And its more than 1 comcast email address.
Any ideas?
rickparyAsked:
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war1Connect With a Mentor Commented:
Rickpary,

Glad you are able to get to one site with DNS lookup.  Could you do so with the other site?  You may want to clear your DNS cache.

Go to Start > Run and type CMD
and hit <Enter>

When you get a command prompt, type ipconfig /flushdns
and hit <Enter>
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David LeeCommented:
Hi rickpary,

What message, non-delivery report, is the client getting back?

Cheers!
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rickparyAuthor Commented:
Your message did not reach some or all of the intended recipients.

      Subject:             xxxxxxx
      Sent:                 3/20/2006 10:17 AM

The following recipient(s) could not be reached:
sterlingxxxxxx@comcast.net on 3/20/2006 10:17 AM

There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.

<pmdc.pm.local #5.5.0 smtp;521-EHLO/HELO from sender 207.148.215.122 does not map to pmdc.pm.local in DNS>

 

 
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rickparyAuthor Commented:
I also checked the blacklists and dont seem to find us anywhere so now Im puzzled...
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war1Commented:
Greetings, rickpary !

1. In the Comcast account settings in Outlook, make sure outgoing server requires authenticiation is selected.
Make sure the SMTP server name, port number, and login address is correct.  Is the login address full email address or just username?

2. Recreate the Comcast account.  Delete the account in Outlook. Recreate it.

3.  Create a new Outlook profile for problem user.

Best wishes!
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rickparyAuthor Commented:
Not a comcast account.
Its a company running an exchange server 2000 and a fractionalized T1.
So that does not help
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war1Commented:
Sorry, I misread you post.  You are sending to a Comcast address.  

Since this one user is the only one having the problem, create a new Outlook profile or Exchange profile for the user.
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rickparyAuthor Commented:
I appreciate your help but it seems to be any one with a comcast.net domain
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war1Commented:
You said other users in your domain do not have problem sending to Comcast, only this one user. So it seems to the user profile is corrupt.  If other cannot send to Comcast, then it is Comcast blocking your domain.  Do you use dynamic IP address?  Comcast uses SORBS blacklist, which blocks dynamic IP addresses.
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upul007Commented:
Hi,

I believe that there is no issue with the users outlook. Since the user gets a server generated NDR from your email server and that other emails to other addresses get delivered is proof of this.  

It cannot be DNS poisoning on the server either as other users are able to send to the same domain without a problem through the same email server. So that rules out your email server having an issue as well.

Are you on a network environment?

Is it possible that your client could be blocked from the comcast.net side? Any way that sterling could confirm this.

If the user is not on a network, there may be other issues.

awaiting your reply,

Upul



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rickparyAuthor Commented:
Well, as it turns out, all users on that server cannot send to a comcast address.
I am using GSI Spam Filter and Trend Micro Antivirus.
I have two domains there, (2 servers) and the people on the other send fine.
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war1Commented:
Check what on the server is blocking Comcast.  You may need to allow Comcast in GSI Spam Filter.

Check if Trend Micro AV is blocking the domain.  

Check if firewall is blocking Comcast.
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upul007Commented:
The server that cannot send emails to comcastmay have an incorrect comcast IP set up. remove all instances of comcast from that server. New entries will get generated automatically when a new email is sent.

Alternatively, you could check if the DNS entries for comcast is properly set up using the results from the DNSReport found at www.dnsreport.com.

Comcast may have blocked either the server domain (not likely if both servers are on the same domain) or your server IP (real IP). You may need to verify with comcast support on this.

Since other emails are actually getting to all recipients except comcast, it is highly likely that either the DNS entry is at fault or comcast had blocked emails coming from that server.

Good Luck

Upul
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war1Commented:
Rickpary, any update?
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jwpacoCommented:
I am running an Exchange 03 server and I am getting the same problem. I think it may be due to our MX record. We have POP3 connectors set up to poll our email from an offsite facility but all email we send out goes out through the local SMTP server. When Comcast tries to validate my email, they are checking the MX record which doesn't match the IP for the mail.mydomain.com record since we are hosting that record out. What I am wondering is how to get this to work with an internal SMTP server sending email and an external email server receiving email for my domain. Thanks.
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PanicXCommented:
I recently resolved this issue by correcting the FQDN listed for the Advanced Delivery Options of the Default SMTP Virtual Server in Exchange System Manager.

Basically my MX record pointed at mail.domain.com but my EHLO/HELO response only listed domain.com.
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dprenevostCommented:
I am having the same problem with SBS 2003 exchange server.  

(domain).com #5.5.0 smtp;521-EHLO/HELO from sender xxx.xxx.xxx.xxx does not map to (domain).com in DNS

Any new updates on this?

Dan
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rickparyAuthor Commented:
In one of my two instances I solved the issue as follows:
I went to http://www.dnsstuff.com and did a reverse dns lookup and found no entries for reverse dns. I called the ISP and had them add it. Solved my problem. Comcast, Earthlink & AOL were all affected by this.
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upul007Commented:
If all of you found www.dnsstuff.com useful, it's a good idea to do a dnsreport through the link to www.dnsreport.com and have the output filed so that if there are any settings which may get changed changed, you will know how it used to be before.

Those two sites have in the past saved us a lot of trouble over certain issues as well.
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upul007Commented:
Yeah, most big domains do not accept emails without reverse DNS entries. There is another record which you may be interested in. It is the SPF record. The details are available on your DNSReport. Please ask the ISP to add that as well.

Glad your issue was fixed.

Good Luck!

Upul
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