Delivery Status Notification (Delay)

I am using Exchange 2003.  I have a user that is trying to contact one of our customers.  Every time the user receives the following message back:

This is an automatically generated Delivery Status Notification.



Delivery to the following recipients has been delayed.

I have checked the queues in Exchange and the users messages are still queued up.

I did some digging around here on EE and found these troubleshooting steps posted in a previous question located here:

Try the following.

- Open a command prompt.
- Type "NSLOOKUP" and press enter.
- Type "SET TYPE=MX" and press enter.
- Type in the domain name of the address that is giving you problems.  For instance, if you are trying to send to, you would type "" and press enter.
- A list should appear.  This is a list of the mail servers (DNS MX records) that are assigned to that computer.  
- Look for the server name with the lowest preference number.  If they are all the same preference, just use one.  In our example, it is
- Type "exit" and press enter to quit NSLOOKUP.
- Try to ping the address.
- If successful, try to connect to the mail server manually:
- Type "telnet 25" and press enter, substituting the appropriate server name.
- You should see a server banner message (see example).
<<< Do not make any typos on the next commands, or the commands will fail.  Backspace will not usually work.  If you mess up a command, press enter and type the command again. >>>
- Type "HELO" and press enter (you might not see what you type.  This is normal).
- Type "mail from:<>" substituting your address and press enter.
- Type "rcpt to:<>" substituting their address
- Type "data" and press enter.
- Type "Subject: Test message" and press enter TWICE.
- Type a short message.  When you are done, press enter, type a period, and press enter again to end the message.
- Type "quit" and press enter to exit.

When I attempt to telnet into their mail server I receive this message back:

550 RBL rejection: local dynamic IP address <my external IP>

Any thoughts on why these messages are not being delivered?  The domain of the person we are trying to contact is


csimmons1324IT ManagerAsked:
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It isn't them, it is you;

>>550 RBL rejection: local dynamic IP address <my external IP>

They don't like your IP address - either because your ISP sold you out, or because you have an invalid PTR record.

Talk to your ISP about fixing it, or create an SMTP connector for this problem domain to route mail through the ISPs smarthost ->

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csimmons1324IT ManagerAuthor Commented:

I recently noticed that our DC does not have a Reverse Lookup Zone configured.  This has nothing to do with this problem, correct?  By not having a Reverse Lookup Zone configured, nothing internally can resolve an IP address to a Name, correct?
Internally does not matter at all.  Externally is the problem.
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csimmons1324IT ManagerAuthor Commented:
When I do a reverse dns lookup of our company's IP address on the PTR record comes back to  So it appears that the PTR record is OK.  Our ISP is Verizon so I don't think that should be a problem since they are a large service provider.  

I can always set the connector, I would just like to figure out exactly what is going wrong.
Give me your domain and I will test it
csimmons1324IT ManagerAuthor Commented:
The domain is vanairinc.


The only thing wrong with your domain is that your MX record has an incorrect weight of 0 (it should be 10) but that would not be stopping your mail out.

Can you try telnetting to this problem domain again and seeing if you get the same error?
csimmons1324IT ManagerAuthor Commented:
I tried to telnet into and got the same error.
csimmons1324IT ManagerAuthor Commented:
I been very busy and I apologize for not responding.  It turned out our IP was being blocked by their ISP for spam reasons.  Working with the customer we were trying to contact and their ISP we got our IP address removed from their blacklist.
kieran_b: how are you testing the domain?
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