When sending e-mail to only this one comany a 5.1.1 Error message is generated.

Posted on 2006-06-19
Last Modified: 2010-03-06
I have a company, I will call XYZ, that is using SBS and they use Exchange server for e-mail. Everything is working OK except when they send e-mail to this one and only this one company, I will call this company ABC, they get a 5.1.1 error stating that “The account does not exist at this organization this message was sent to”. This message is generated by Company XYZ exchange server. Any e-mail sent to any person at Company ABC is not delivered and we get the same 5.1.1 code. Now here is what is strange. If you send Company ABC e-mail from any other source out side of Company XYZ the e-mail will arrive. Company XYZ has no problems with other companies.

Company ABC is using POP 3 accounts to get their e-mail and their ISP states nothing is wrong on their end as other people can send mail to ABC.

Company XYZ is setup using a Smart Host to their ISP. I call this ISP and ask them to send Company ABC a test e-mail. I knew ABC would get it but I wanted to be sure and sure enough ABC got the e-mail.

I’m thinking that something is wrong at Company ABC ISP and may be a reverse lookup problem of some sort.

My question: Is their something I am missing on XYZ Exchange server that can cause this problem?

Question by:CHFFriday
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LVL 35

Expert Comment

ID: 16934659
if the NDR is coming from your Exchange server then that means that the email is not leaving your exchange server. try doing a message tracking and check
LVL 104

Expert Comment

ID: 16935608
Have you checked whether the message is being delivered to the correct server?

On the Exchange server itself, drop in to a command prompt.

Type in


and press enter
Then type in

set type=mx

and press enter

then enter the domain name that you are having problems with (

You will get back some MX records.

Then go to and use their MX record lookup tools and see if they are the same.


Author Comment

ID: 16937014
Did as you requested. MX record lookup returned the same info as nslookup. The name resolves to three IP Addresses. This is a BIG ISP so I think this may be OK. What do you think?

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LVL 104

Accepted Solution

Sembee earned 500 total points
ID: 16937959
You actually get this kind of problem more often with big ISPs then smaller ones - as they will have a cluster of machines that answer to email requests.

What is happening is that the server your server is connecting to doesn't recognise the domain. This is usually down to an ISP error.
You might find that clearing the DNS cache on the server and in the DNS applet might allow the email to flow through.


Author Comment

ID: 16946773
Just to update you. Today we moved the XYZ Company's DNS records to a new ISP. A smaller one that I use allot. It semed to fix the problem BUT this afternoon it came back. I have some other data that will blow you mine but I don't have it all put together let.

I will get back to you tomorrow.


Author Comment

ID: 16955114
Every thing is working. Had to wait for the propagation to take place. After 24 hours I have no 5.1.1 errors. Moving from the old ISP to the new ISP solved the problem. I will give the points to you as you headed me in the right direction.


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