I understand that SPF and DKIM are not specifically required at this point but nice to have(s).
DKIM - If my research is correct this gets setup on the actual email server?
SPF - OK. We use Time Warner for our ISP. We have static IP address. In order to have reverse DNS setup, we had to have Time Warner add it to their DNS servers. Is this the same case with SPF? I would create the TXT DNS entry, provide it to them and then they would have to put it on their server?
FYI: Our infrastructure is -
Exchange Server 2007 setup behind a Hardware firewall with only SMTP and HTTPS ports open and forwarded to the Exchange Server. External(firewall) static IP with MX record and reveres DNS setup