What is the Email Deliverability feature within cPanel?
This interface allows a customer to identify problems with DKIM, SPF, and PTR records for a domain.
The system modifies the DKIM and SPF records if the authoritative nameservers for the customer’s domain DNS record exist on the server. If it does not, then the system will not add the records, and it will report the problem/s that it identified.
Email Deliverability (cPanel Docs)