Sender Policy Framework (SPF) is an email authentication system that allows a receiving email host to verify that the sending host is authorized by the domain’s owner.
To implement SPF, you need to add a specially formatted TXT record to your DNS records. To start, create a list of all domains and IP addresses that are authorized to send mail on your behalf. This list will include the IP address of your webhost, your newsletter company, and your email client. Then ask your email or web host for help in formatting the specific TXT record you need.
The following is a sample of what a correctly formatted SPF record looks like:
TXT example.com. “v=spf1 ip4:192.0.2.0/24 ip4:198.51.100.123 a -all”