Exchange Server - Multiple domains and reverse DNS on Exchange 2003

How do I setup multiple email domains and have each use its own IP?

I host multiple domains on my SBS 2003 / Exchange 2003 server. I need to be able to send email from each domain and have the reverse DNS match. I have multiple static IPs. Each static IP already has the reverse DNS setup by my ISP. I have added a second NIC to the server and configured it to pull one of my static IPs.

I thought I would only need to add a 2nd SMTP virtual server using the new IP (which I did) but how do I make the email sent from user1@domain1.com use the default SMTP server and email from user2@domain2.com use the new SMTP virtual server?

I setup user2 to have domain2 as the default SMTP email address in the user properties. I also set the FQDN on the 2nd SMTP server to domain2.com.

How do I make this work, or is this totally the wrong approach?

It is not necessary to use multiple IP addresses to send for multiple domains.

A reverse DNS (or PTR) record is only concerned with the 'reverse lookup zone', which is IP based. It is not concerned with the domain, nor is mail.

The important thing is that you have a reverse DNS record set up for the IP address. It is generally a good idea to use on of the primary domains you use to send mail. Set up a corresponding 'A' record for the domain in question that points to the IP address and you are in business.

You should set the SMTP virtual server to use the same as the reverse DNS record.

It is a common misconception, but the reverse DNS (or PTR) record does not need to match the domain of the mail messages you are sending. The important think is that you have a valid record.

Shaun

Problem is, if the domain in the header "from field" does not match the reverse DNS, then the SPF rating grows and my email sometimes gets flagged as SPAM. I have confirmed this with google mail by sending the exact same email through an IP that has a reverse DNS that matches the "from" and then again through an IP that does not match the "from" (but does have a valid record.

There must be a way to host multiple email domains with each having it's own IP.

You are mixing up SPF and reverse-DNS which are completely seperate unrelated concepts.

For SPF to pass, you will need to have the IP address listed in EVERY SPF record you have for EVERY domain you are going to use for the sending IP address.

In terms of routing using multiple IP addresses, this can not be achieved using Exchange, it will route mail based on destination, not source. That is just the nature of Exchange.

You shouldn't have any problems at all using one IP to send for multiple domains, I have set this scenario up hundreds of times.

Shaun