The record that says who may send.
WHAT IT DOES
Lists the servers permitted to send mail for your domain. Receivers check the sending server against it.
THE FORMAT
A TXT record beginning v=spf1, listing mechanisms, ending with a policy.
WHAT TO INCLUDE
The hosting server, usually by an include or an a mechanism
Any external sending service: your marketing platform, a transactional service
Nothing else
THE ONE RECORD RULE
A domain must have exactly one SPF record.
Two records is an error, and both fail. This is the most common SPF mistake.
If you add a sending service, add its mechanism to the existing record rather than creating a second.
THE ENDING
Most domains end with a soft fail or a hard fail policy. cPanel > Email Deliverability sets a sensible default.
THE LOOKUP LIMIT
SPF permits a limited number of DNS lookups. Including several services can exceed it, causing failure.
If you include more than a few services, check the count.
CHECKING
A lookup for TXT records shows what is published. There should be exactly one starting v=spf1.
