Question : SPF Record placement

I'm trying to get my hands around SPF records and how to implement them for my specific scenario.  
I have a single server in a colocaction facility.  This server has a single IP and I have 2 virtual domains on the box.  Lets say the hostname for the box is www.server.com.  The virtual hosts are virtual1.com and virtual2.com.  Both the virtual dot coms have mailing lists associated with them.  So, when members of the list send a message to [email protected], it sends out to all members through the www.server.com server.

I can see how SPF records work, what I'm missing is where to assign them.  I have control of DNS through a web interface where there's a faciltiy to add SPF records.  

Do I add SPF records for both domains virtual1.com and virtual2.com respectively or do I add an SPF to www.server.com (the name the lists send through), that allows the 2 virtual domains through?

I've been playing with the SPF Wizard on openspf.org, which is excellent for syntax.  If someone could please help me get my hands around my scenario, I'm off to the races.  My yahoo.com users will also thank you.  

Answer : SPF Record placement

There is a very basic rule to follow:

You need to include ALL servers that send mail for a domain.

So, if you are setting SPF for 2 domains, you will need to add the same TXT file to BOTH domain DNS space if the outbound IP is the same.

It is the IP addresses that you need to reference. You can use 'A' record to reference, but this again will point to an IP address.

Find out what the public IP is that is used to send outbound mail from this location and that is what to include. You can look at the email headers to get the IP address.
 
Shaun