A Guide for Senders and Receivers - The Role of SPF and DMARC in Email Authentication

Created on 1 April, 2023 | 520 views | 3 minutes read

Image source: sendpost.io

Email is a vital communication tool, but it is also vulnerable to spoofing and phishing attacks. To combat these threats, email
authentication protocols like SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting, and Conformance)
have been developed. This article provides a comprehensive guide on the role of SPF and DMARC in email authentication, helping
senders and receivers protect their domains and ensure secure email communication.

Understanding SPF: Verifying Sender Authenticity

SPF is a widely adopted email authentication protocol that helps verify the authenticity of the sender's domain. SPF uses DNS
records to define a list of authorized email servers that are allowed to send emails on behalf of a specific domain. When an
email is received, the recipient's mail server can check the SPF record of the sender's domain to verify if the email originated
from an authorized server. If the check fails, the email may be treated as suspicious or potentially fraudulent.

The Importance of DMARC: Enhancing Email Authentication

While SPF provides a mechanism to validate the sender's domain, DMARC takes email authentication to the next level. DMARC allows
domain owners to specify policies for handling emails that fail SPF or DKIM (DomainKeys Identified Mail) checks. With DMARC,
senders can instruct receiving mail servers on how to handle emails that do not pass authentication checks, such as quarantining
or rejecting them. Additionally, DMARC enables domain owners to receive feedback reports on email authentication results, providing
valuable insights into potential abuse or unauthorized email activity.

Setting Up SPF and DMARC Records

Configuring SPF and DMARC involves updating DNS records for the sender's domain. Here's a brief overview of the setup process:

1. SPF Record

To set up SPF, the domain owner needs to create a DNS TXT record containing the list of authorized email servers. The SPF record
specifies the mechanisms and qualifiers for SPF checks. These include the IP addresses, hostnames, or include statements that
define the allowed email sources. Once the SPF record is published, receiving mail servers can verify the sender's domain authenticity
by checking the SPF record during the email delivery process.

2. DMARC Record

DMARC requires the creation of a DNS TXT record that defines the DMARC policy for the domain. The DMARC record includes parameters
such as the policy mode (none, quarantine, or reject), the percentage of emails to which the policy applies, and the email address
for receiving DMARC aggregate and forensic reports. DMARC enforcement can be gradually implemented, starting with monitoring mode
before moving to quarantine or reject mode.

Benefits of SPF and DMARC for Senders and Receivers

SPF and DMARC provide significant benefits for both senders and receivers:

1. Sender Benefits

  • Enhanced Sender Reputation: Implementing SPF and DMARC helps establish a positive sender reputation by authenticating email
    sources and reducing the risk of spoofing.

  • Improved Deliverability: Email messages that pass SPF and DMARC checks are more likely to reach recipients' inboxes rather
    than being marked as spam or phishing attempts.

  • Brand Protection: By enforcing email authentication, senders can protect their brand reputation from being compromised by
    unauthorized senders.

2. Receiver Benefits

  • Reduced Spam and Phishing: SPF and DMARC help receivers filter out spam and phishing emails by verifying the authenticity
    of the sender's domain.

  • Enhanced Email Security: By implementing DMARC policies, receivers can instruct mail servers on how to handle unauthenticated
    emails, providing an additional layer of protection against malicious activity.

  • Reporting and Insights: DMARC reports provide valuable feedback to receivers, allowing them to monitor email authentication
    results, identify potential abuse, and take necessary actions to ensure secure email communication.


SPF and DMARC play a crucial role in email authentication, helping senders protect their domains and receivers filter out potentially
malicious emails. By implementing these protocols, senders can establish their authenticity, improve deliverability, and safeguard
their brand reputation. Receivers, on the other hand, can enhance email security, reduce spam and phishing threats, and gain
valuable insights into email authentication results. Together, SPF and DMARC contribute to a more secure and trustworthy email
communication ecosystem.

Updated on 29 May, 2024