SPF (Sender Policy Framework) Validation tool allows users to determine whether there exists some SPF record in type TXT of DNS records of the subjected domain or host. The validation is done by validating the format of SPF records of the domain and determining if the data is valid and should be working or not.
SPF record is a type of TXT DNS Record that allows specific hosts to send a trusted email via any email address of a domain. The trusted email means that the owner of a domain specifies which servers are allowed to send email using my domain's email addresses. For this purpose, the domain owner has to add server IPs or hosts as SPF records in the DNS of a domain.
The next time whenever an email has been sent using the domain's email addresses, the receiving servers verifies if the sender IP exists in SPF records. If the sender IP is not found in SPF records, then the email may most probably be moved into junk.
SPF record validation tool works by checking if a domain's DNS records contain SPF records in type TXT of DNS records. If SPF records exist, they are checked if entered correctly. To verify its validity, the format of the records is checked against the recommended method for adding SPF records. The errors and warnings are then displayed as result.