We have an IIS 5 server sending ecommerce transaction
email responses straight out through the IIS SMTP virtual
server. We do not have the ability to pass these messages
through a registered domain or a registered server name.
How can we avoid being classified as a SPAM source? Is a
reverse DNS lookup our only option? If so, should the
reverse lookup be configured at our ISP's end? Our ISP
currently provides our public IPs and internet zone files.

On Mon, 26 Jul 2004 05:15:15 -0700, "MEB"
[quoted text, click to view]

To avoid getting balcklisted, make sure you don't relay. If you're
getting identified as spam for another reason, you need to deal with
that reason.

[quoted text, click to view]

Most spam filters are now checking reverse DNS to ensure there is a
lookup, but not necessarily that it goes to a specific domain.

[quoted text, click to view]

Then they need to do the reverse DNS zone.

For many filters, an email server configured with just an IP address
and no host name is an indicator of a compromised server and likely to
send spam. So you may need to configure a host/domain name to ensure
getting through.

On Mon, 26 Jul 2004 05:15:15 -0700, "MEB"
[quoted text, click to view]

Read this KB article :

HOW TO: Prevent Mail Relay in the IIS 5.0 SMTP Server in Windows 2000
http://support.microsoft.com/?id=310356


Regards,

Paul Lynch