Ensuring Email Security with SPF, DKIM and DMARC

Evolution of Email Security Policies

Over the last decade, email providers have tightened security with SPF, DKIM, and DMARC. From 2017 to 2020, enforcement strengthened, and by 2023, Microsoft adopted stricter DMARC handling, honoring sender policies for rejection and quarantine more closely.

Download Whitepaper EnsuringEmailSecurity.pdf

SPF (Sender Policy Framework)

SPF acts as a 'guest list' for email senders, telling receiving email servers which servers are authorized to send emails on behalf of your domain. Proper SPF setup is crucial for blocking spammers, protecting brand reputation, and ensuring message deliverability.

Why SPF is Important
  1. Blocks Spoofers: SPF prevents unauthorized people from impersonating your company.
  2. Protects Brand Reputation: Reduces chances of bad actors damaging your brand’s trust.
  3. Improves Deliverability: Helps keep legitimate emails from being marked as spam.
  4. Supports DMARC: SPF is critical for full DMARC validation, preventing security gaps.

DKIM (DomainKeys Identified Mail)

DKIM allows your emails to 'sign off' with a digital signature to verify authenticity. A correctly configured DKIM signature enhances email integrity and security.

Importance of DKIM
  1. Ensures Email Integrity: DKIM signatures guarantee that emails haven’t been altered.
  2. Supports DMARC Compliance: DMARC relies on DKIM to verify legitimate emails.
  3. Helps with Deliverability: Messages with valid DKIM signatures are less likely to end up in spam.

DMARC (Domain-based Message Authentication, Reporting, and Conformance)

DMARC acts as a 'security checkpoint,' allowing only authorized senders to use your domain. It protects your business from phishing and helps build trust with clients.

Why DMARC Matters
  1. Preventing Imposters: DMARC blocks fake emails impersonating your company.
  2. Protecting Brand Reputation: Prevents scammers from harming your brand’s reputation.
  3. Building Client Trust: Clients feel safer knowing your emails are genuine.
Impact of Incorrect SPF, DKIM, or DMARC Configuration

Incorrect configurations can harm email deliverability. Major email providers like Gmail, Microsoft, and Yahoo may filter, block, or quarantine emails lacking proper SPF, DKIM, or DMARC.

  1. Emails Land in Spam: Poor setup can lead to emails going directly to spam.
  2. Emails are Rejected or Blocked: Providers may reject messages failing DMARC policies.
  3. Reduced Sender Reputation: Frequent spam flags due to misconfigurations harm your reputation.

Michael Scheidell, CISSP, CCISO, CRISC, SMIEE

Michael Scheidell is a seasoned cybersecurity expert with extensive experience in email security and open-source software development. As the Chief Technology Officer at SECNAP Network Security Corporation, he has been instrumental in developing SpammerTrap®, an advanced email security solution designed to protect organizations from spam, phishing, and malware threats. Scheidell has also contributed significantly to the FreeBSD community, particularly in maintaining and updating the SpamAssassin port, a widely used open-source spam filtering platform. His work ensures that FreeBSD users have access to the latest SpamAssassin features and security updates. Under his leadership, SECNAP's SpammerTrap® has received positive reviews for its effectiveness in filtering unwanted emails and its user-friendly interface. Additionally, Scheidell has been involved in discussions and developments related to Rule18, a component of SpamAssassin, demonstrating his commitment to enhancing email security through community collaboration and technological innovation.