When you say 'you should use an IP address that E-mail servers can use to correctly reverse -verify the source', do you mean use an IP address with any valid reverse address, or do you mean use an IP that has the email address' domain in the reverse zone?
For example, I have static IP DSL service through Verizon, and the PTP for my IP is a Verizon-DSL name. Would I then have to use, say, my Verizon e-mail address for verification?