The Sender Policy Framework (SPF) is a vital email authentication method designed to detect forging sender addresses during the delivery of the email.
Within SPF, there are two key terms that users and engineers should understand: "hard fail" and "soft fail."
Both these mechanisms impact how the recipient's mail server treats emails from unspecified locations.
Hard Fail
A hard fail means that the recipient's mail server will outright reject any emails sent from locations that are not specified in the SPF record. This offers strict enforcement and is represented by the -all at the end of the SPF record.
v=spf1 +a +mx +ip4 187.10.190.2 -all
Soft Fail
On the other hand, a soft fail is more lenient. While it permits the recipient's mail server to accept messages sent from locations not specified in the SPF record, some email services may still mark these messages as suspicious or spam. Soft fails are often used during the testing phase of SPF record changes and are represented by the ~all at the end of the SPF record.
v=spf1 +a +mx +ip4 187.10.190.2 ~all
Why Is This Needed?
- Security: A hard fail helps in creating a robust defense against email spoofing and phishing attempts, ensuring only legitimate emails are accepted.
- Flexibility: Soft fail provides a testing ground to ensure the SPF record is working as intended without risking legitimate emails being rejected. It allows for gradual implementation and monitoring.
- Compliance with Email Services: Different email providers may interpret soft fails differently. Understanding the distinction helps in configuring the SPF records that align best with different recipient email services.
In conclusion, the choice between hard fail and soft fail is a strategic decision based on the security needs, testing requirements, and alignment with various email services.
Proper understanding and implementation of these fail to play a crucial role in the effective use of SPF within cPanel and Plesk.
