General discussion


E2K SMTP problems with certain domains

By pcs ·
We're running a single Exchange 2000 Server. We can't send mail to certain
addresses (actually domains) but these addresses can be reached from another
server (such as Yahoo Mail or Hotmail). Here's what I've done so far:

1. The system logs don't contain any useful information, just the fact that
delivery failed.

2. I can telnet from the Exchange server to the remote SMTP server, manually
input the SMTP commands, and send a message that way.

3. The error on the queue (under the SMTP virtual server) is "The remote
server did not respond to a connection attempt." However, from checking the
logs on the firewall, the server has not actually tried to connect to the
remote server.

4. The server is using external DNS servers run by our service provider.
From the firewall logs, it looks like the server is making as many as five
DNS lookups for every remote server it connects to. I don't know if this is
normal, a problem, or even related.

5. By looking at the DNS tables, all of the addresses that experience this
problem are configured as follows: The MX record specifies a canonical name
(alias) which then points to an address record. Put another way... MX Alias A 304.23.56.5
Technically, this is a DNS no-no, but that hasn't stopped anyone.

TechNet article Q153001 addresses a similar issue, but under that scenario, I should see activity to the remote host in both the firewall and SMTP logs. There is none.

I think that somehow the DNS table configuration throws off Exchange's ability to correctly process either the message or the address or both. Is that right?
How can we fixthis (assuming we don't want to call all these people and
persuade them to fix their DNS tables)?

Phillip Shannon
Assistant Manager of IS
Bury+Partners, Inc.

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E2K SMTP problems with certain domains

by duwaned In reply to E2K SMTP problems with ce ...

As a workaround until they fix their DNS, why not put entries into your hosts file for their mail server??

This is not going to fix the problem, but will hopefully get your mail out successfully until they eventually sort out their DNS entries.

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E2K SMTP problems with certain domains

by pcs In reply to E2K SMTP problems with ce ...

In the course of implementing your suggestion, I discovered the real source of the problem. In order to get Exchange 2000 to read the hosts file, you have to turn off using external DNS servers for the virtual SMTP server. There is a bug in the external DNS routine, so disabling that feature causes all the DNS-related problems to go away as DNS lookups now work correctly. This is fully documented in Microsoft's Knowledge Base Q280794.

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E2K SMTP problems with certain domains

by pcs In reply to E2K SMTP problems with ce ...

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