EMF does not identify itself with the correct host name

Summary:

EMF, like any other SMTP Relay, identifies itself in two cases.

First, when a client connects to us:
220 server1.tumbleweed.com SMTP Relay Service ready

Second, when we are connecting outbound, in the "HELO" (or "EHLO") greeting:
HELO server1.tumbleweed.com

Detailed Information:

If your server does not identify itself using its correct name or non-fully qualified domain name (FQDN), some destination domains may reject your messages with errors similar to the following:

Unexpected recipient failure
504 server1: Helo command rejected: need fully-qualified hostname

or

any other indication that your EMF server identified itself as a host that does not correspond to the domain that the IP address of your server resolves to. In other words, you failed a reverse DNS lookup (RDNS).

Each EMF 5.x and later relay service gets the hostname it uses to identify itself from the operating system's TCP/IP properties. To adjust the hostname identification, you may need to adjust those properties.

In particular, the EMF SMTP Relay Service looks for the Registry values named "Hostname" and "Domain" under the key

HKLM\System\CurrentControlSet\Services\Tcpip\Parameters

If the "Domain" value is missing, we will try to pick up the value of "DhcpDomain". Although Windows stores these values in the registry, they are usually edited from the Network control panel, TCP/IP properties.

Resolution:

Modify the TCP/IP Properties:

For Windows 2003:
1. go to Properties for My Computer
2. go to the Computer Name tab
3. click the Change button
4. click the More button
5. add the "Primary DNS suffix of this computer"
(i.e. for server1.tumbleweed.com, the server name is "server1" and the Primary DNS suffix is "tumbleweed.com")

For Windows 2000:
1. go to Properties for My Computer
2. go to the Network Identification tab
3. click the Properties button
4. click the More button
5. add the "Primary DNS suffix of this computer"
(i.e. for server1.tumbleweed.com, the server name is "server1" and the Primary DNS suffix is "tumbleweed.com")

For NT 4.0:
1. go to properties for Network Neighborhood
2. go to the Protocols tab, then properties for TCP/IP
3. go to the DNS tab
4. make sure both a host name and domain are entered

Alternatively, you can override the hostname for all relay machines accessing this database by specifying the name in the "Relay Host Name" field in the EMF SMTP Relay setup page in Web Admin. This will have the effect of setting the hostname for all SMTP Relay services using that database to the same string.

Modifying the "Host Name" will affect all of the following:

1. The message returned in response to new inbound connections, i.e., the text after the 220 response.
2. The message returned in response to the EHLO command.
3. The message returned in response to a QUIT command.
4. The Received: header inserted into all messages received by the inbound SMTP Relay.
5. The HELO and EHLO commands generated by the outbound SMTP Relay.
6. The Message-Id: header generated for new notifications created by the EMF SMTP Relay.
7. The Reporting-MTA: header in delivery status notifications.

For example, in one case, an EMF user had moved her EMF server from a Windows domain to a workgroup, and removed the fully-qualified server name from the server's TCP/IP properties. This in turn removed the appearance of the FQDN in the relay HELO command. Some remote servers, however, still required the FQDN in the HELO command. To correct this problem, she specified the fully-qualified server name in the "Host Name" field on the Relays Set Up page.

In another use case, the user's EMF box was in a workgroup, but My Computer Properties specified both the computer name and the domain suffix. However, EMF was not placing the FQDN in the EHLO command. We suspected that Windows was not returning the FQDN to EMF because the machine was in a workgroup. As above, we corrected the problem by specifying the fully-qualified server name in the "Host Name" field on the Relays Set Up page. At this point, the recommendation is to use this solution whenever the EMF server is in a workgroup.