Understanding SPF and the 550 SPF Check Failed Error
Sender Policy Framework (SPF) is an email authentication protocol defined in RFC 7208. It allows a domain owner to specify which mail servers are authorized to send email on behalf of their domain. SPF helps prevent email spoofing and improves email deliverability.
When a receiving mail server processes an incoming email, it performs an SPF check. This check compares the sending server's IP address against the authorized list in the sender's SPF record. If the IP address is not authorized, the SPF check fails.
A 550 SPF Check Failed error indicates that the receiving mail server rejected the email. This rejection occurs because the sending IP address did not match any authorized entries in the domain's SPF record. Such failures negatively impact email deliverability and sender reputation.
Common SPF Misconfigurations and Their Impact
