Our company has a SMTP server that sends mail out on behalf of our customers. So a customer would log into our system, go to a specific section, and can fill out a form to send an Email to whoever they want as whoever they want from their domain, or any other domain for that matter. So if it was email@example.com he would just put in that address, he could also put in firstname.lastname@example.org. However assuming he is putting in his correct domain sometimes the recipient marks it as spam because it is coming from our system not say their Outlook.
In order to resolve the delivery issues would it be accurate to tell them that they should create/update a SPF record on their domain as follows?
v=spf1 ip4:126.96.36.199 -all
At the moment we don't have a DNS A record pointing at this IP but I could create one if that would be better. In that case would it be this instead?
v=spf1 include:spf.ourdomain.com -all