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cannot email optonline.net

Two days ago we started to be unable to email anyone with an optonline.net email address.
We are running Exchange 2000 and Server 2000.

The only thing that has changed in the system is that I have installed Exchange Standard 2003 on Exchange 2003 Server in anticipation of upgrading.  Only one mailbox has been moved.  

This is the error message I receive

 There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <exchange.dss.com #5.5.0 smtp;550 <user***@optonline.net>: Recipient address rejected: User unknown in relay recipient table>

I did an nslookup and it returned a valid record for optonline.net

Any help would be greatly apreciated!

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csocci
Asked:
csocci
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1 Solution
 
SembeeCommented:
That isn't an Exchange error, so it is coming from upstream from you.
Do you send your email directly or via a smart host?

Simon.
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csocciAuthor Commented:
We send email directly.
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SembeeCommented:
As a test, try setting up an SMTP Connector for this one domain to send via your ISPs SMTP server. See if the message goes through then. http://www.amset.info/exchange/smtp-connector.asp

Another thing you could do, instead of the above, is use message tracking to see which server the message is being delivered to.
Have you got message tracking turned on?
What might be happening is that the server your server is trying to use has a problem. If it is always trying to use the same server, then you would always get the same error. You could try flushing your DNS cache on the server and the DNS servers so that the lookup has to be done again.

I am sure this is a problem outside of Exchange.

Simon.
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csocciAuthor Commented:
Here is what the message tracker returned

SMTP Store Driver: Message Submitted from Store
SMTP: Message Submitted to Advanced Queuing
SMTP: Started Message Submission to Advanced Queue
SMTP: Message Submitted to Categorizer
SMTP: Started Outbound Transfer of Message
SMTP: Non-Delivered Report (NDR) Generated


I flushed the DNS cache yesterday to no avail.

Thanks for the info...I'm gonna try the SMTP connector


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SembeeCommented:
Didn't show which server it was trying to use, which is a pity.

Simon.
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csocciAuthor Commented:
in another pane next to these messages was the local servers name.

I tryed the SMTP connector with no luck.  However, I am not aware of a smart host we can use so I set it up with "Use DNS to route to each address space on this connector"

any more ideas?  Should I ask my boss if we have access to a smart host?

Thanks.
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SembeeCommented:
Using DNS to route rather defeats the object of using an SMTP Connector. The whole point was to route your email via another server so that you could see if the problem followed.

Smart host is basically an SMTP Server. What I normally suggest is to look on your ISPs web site for the SMTP server address that they give to Outlook Express users. Then test to see if you can connect to that server on port 25, if so, configure that as a smart host.

Simon.
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csocciAuthor Commented:
After doing an nslookup I tried to telnet into port 25.  I am able to from my laptop but not from the exchange server.
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csocciAuthor Commented:
I tried to telnet into port 25 of optonline.net mail servers

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SembeeCommented:
You tried to telnet in to the optonline server from the Exchange server and failed, but could from a laptop?
Thats interesting.
Does the laptop have a different external IP address to the Exchange server?
Check here: http://checkip.dyndns.org/

Simon.
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csocciAuthor Commented:
Yes, the laptop does have a different external IP than the Exchange server.

It gets more interesting...we are able to mail to optonline.com but not optonline.net
I accidentally typed .com and it went to my bosses inbox even thought his address is .net

I checked with optonline and they checked our IP and said they weren't blocking us.

I'm stumped.

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SembeeCommented:
The MX records are identical, so there should be no reason why one domain will work and the other will not.

When you tried to telnet in to their MX record servers, did you use the IP address or the host name?
If you used one, try the other.

Simon.
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csocciAuthor Commented:
I think the issue is on optonline's side.  Thanks for your help
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