Email Authentication
SPF, DKIM & DMARC Explained for Businesses
Email remains one of the most common ways cybercriminal attack businesses. Fake emails pretending to come from your company can damage your reputation, trick customers, and lead to data breaches.
Email authentication helps protect your business by proving that emails sent from your domain are legitimate. In Microsoft 365, this is achieved through three key technologies: SPF, DKIM, and DMARC.
🔍 Why Email Authentication Matters
Without proper authentication:
Attackers can impersonate your business
Customers may receive fake emails from your domain
Legitimate emails may land in spam folders
Your brand trust can be damaged
Email authentication protects both your business and your customers.
🛡️ SPF – Who Is Allowed to Send Emails?
Sender Policy Framework (SPF) tells receiving email servers which systems are authorized to send emails on behalf of your domain.
In simple terms:
SPF answers the question, “Is this email coming from an approved source?”
🔐 DKIM – Has the Email Been Altered?
DomainKeys Identified Mail (DKIM) adds a digital signature to outgoing emails. This signature confirms that:
The email was not altered in transit
It truly came from your domain
DKIM protects message integrity and authenticity.
🚦 DMARC – What Should Happen to Fake Emails?
Domain-based Message Authentication, Reporting & Conformance (DMARC) brings SPF and DKIM together and tells email servers what to do when an email fails authentication.
DMARC allows businesses to:
Monitor email activity
Block or quarantine fake emails
Receive reports on spoofing attempts
It’s the final layer of protection.
Protect your brand before attackers exploit it. Contact Tech911 today to secure your business email properly.