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Connection Was dropped by Remote host

We're Running an Exchange 2003 Server, It's been running since about Nov. 2003, and haven't had any problems sending or recieving mail until now.

All of our mail is being sent successfull, except for mail sent to yahoo.com and aol.com

It's not sending back bounce messages, or anything of the sort.

When I look at the job que, and click on the yahoo que or aol que, it says "The connection Was dropped by the Remote Host."

I'm not seeing any NDR's being sent back, it just keeps retrying, until the message expires.

I've checked spam lists, and am not on any of them that I can find.

Has anyone run into this?  
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gdmacmillan

Yes i have run into this.

I guess the questions to ask is who is providing your internet connection. If its a cable company Yahoo and Aol block that range of ip's due to a lot of spam comming out of that range.

The other thing to look at is if they cant do a RDNS lookup on your mx record that could be another reason why your dropped.

Hope that helps.
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ASKER

We use sprint, and according to them, our RDNS and MX records are set correctly.

I'm just not sure what else there is...

our domain is litw.org

When I do an RDNS and MX lookup for those on www.dnsstuff.com, it all looks right.  I'm stumpped on this one...
According to the dns records your email is hosted by sprint and not by you?

 litw.org mx record points to mail.global.sprint.com my guess is that they are doing a reverse dns lookup and because it points to a different domain they just drop you.

What you should have is a mx record that points to a server on your domain ie mail.litw.org
In a way, that is correct.  Sprint is our Spam/Virus filter before it gets to us.  So, if someone were to send us mail it would hit them first, then their service would relay the clean e-mail to us.
But you send directly out or do you relay through the sprint servers?

If you send directly out i would try a smtp connection from your server and see if you get instantly dropped that will tell you right away that your blacklisted.

To do this here's a really good article from microsoft on testing smtp connections.

http://support.microsoft.com/default.aspx?scid=kb;en-us;153119&Product=exch2k

If your blacklisted there's not much you can usually do. I have my own exchange server and run from a cable modem system AOL and Yahoo drop my connections instantly because they have black holed all ip's in the address range serverd up by my cable provider. Im not on any spam lists etc im not a open relay its just a decision by those companies.

Yes I would also add an MX record with a higer cost than sprint to the DNS records, this way if one of the larger companies tries to do a lookup via DNS they will see you in the database.

Try telnetting directly to one of the mx servers for aol via port 25. Use smtp commands, helo, mail from: and rcpt to: and see what the resultant error message is, if you get one.
Found the aswer...  Windows 2003 Server eDNS needed to be disabled according to MS article 832223

Secondly I had to rebuild my DNS root hints.  According to article 249868

Thanks for all your help, but I figured this one out on my own.  No points will be awarded.
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We were also facing the problem of "The connection was dropped by the Remote Host" on our Exchange Server 2003 running on Windows 2000 Standard Server Operating System. We were able to send emails to some domains (yahoo.com was OK) but were unable to send emails to some others including to hotmail.com. All the emails that we were unable to send were being retried by the Exchange Server until it delivered the final non-delivery report to the System Administrator and similar message to the end user. The way we could resolve this problem was to uncheck "Enable Internet E-mail Auto-Protect" in the "Symantec Antivirus" software running on our Exchange Server. Restarted Symantec services and also the "Simple Mail Transfer Protocol (SMTP)" service. Everything came back to normalcy. No queues were seen in the Exchange server and all the previously held "active" states were turned to "ready" state in the Exchange Server.