All of a sudden many of my companies emails are being blocked by Hotmail and many others due to SPF. I've added v=spf1 ip4:18.104.22.168 a mx:hpdist.com ~all to my DNS settings as a TXT record. But this hasn't helped. Is there something server side I need to adjust?
When troubleshooting SPF records, I use http://www.kitterman.com/spf/validate.html. This lets me test DNS records before I push them to the server, that way I know they'll work before I deploy them.