We host many subdomains on "client.domain.com". One of the clients was complaining about the SPF records not having the IP address listed. I've tried setting up the SPF record for "client.domain.com" to include the subdomain's IP address. However my concern is that because we're using SMTP server on IIS to send out the emails, they are still being marked as spoofed. The web app allows you to choose what email domain to send emails out from, and I've tried setting up IIS to relay to an actual email account (using real credentials) but this doesn't work. Emails only get sent out when you set SMTP to allow anonymous connections and for the web app to specify the email account name (without actually putting in the real email credentials).
My question is: will this type of SMTP setup allow for accurate SPF records?