An SPF record is a type of Domain Name Service (DNS) record that identifies which mail servers are permitted to send email on behalf of your domain. The purpose of an SPF record is to prevent spammers from sending messages with sender addresses of your domain.
Missing SPF record allows hackers to send spam emails by using an email address that includes your domain name as its suffix.
Add an SPF record for your domain name at your DNS provider.
Create a new TXT record.
Set the Host field to the name of your subdomain (for example,
firstname.lastname@example.org), or to
@if you do not use a subdomain.
Enter your SPF record for the TXT Value field (for example,
v=spf1 a mx include:secureserver.net ~all).