When managing communications, trust is everything. Unfortunately, the simplicity of basic email protocols lets criminals easily fake the “From” address—a process called email spoofing. This is why every modern domain must implement robust methods for Secure Email Delivery.
We focus on three non-negotiable protocols: SPF, DKIM, and DMARC. These three pillars are set up by the domain owner as DNS TXT records. These publicly accessible instructions tell the rest of the internet exactly how to handle emails coming from their domain.
The Spoofing Problem: Why Authentication is Crucial
To truly appreciate these protocols, consider the problem. Without them, any computer server can send an email claiming to be from your domain. Thus, this verification gap is the main security hole these Secure Email Delivery systems aim to plug.
1-SPF: Sender Policy Framework (The Authorized Carrier):
SPF actively prevents unauthorized servers from sending email on your domain’s behalf. Specifically, it acts as a definitive list of approved mail carriers for your domain.
- Mechanism: The domain owner publishes an SPF record in their DNS. This record explicitly lists all IP addresses and mail servers authorized to send email for that domain.
- The Check: First, when a recipient’s mail server receives an email, it checks the sending server’s IP address against the sender’s SPF record.
- Protection: Furthermore, if the email comes from an IP address not on the authorized list, the SPF check fails. Consequently, this action blocks spammers using unauthorized servers to impersonate your domain. For help generating your first SPF record, we recommend using the free tool provided by (https://easydmarc.com/tools/spf-record-generator).
2-DKIM: DomainKeys Identified Mail (The Tamper-Proof Signature):
DKIM provides a digital signature. In fact, this signature guarantees that the message has not been tampered with in transit. In other words, it assures the recipient that the content they see is the content you sent.
- Mechanism: The domain owner creates an encrypted public/private key pair. The private key signs the outgoing email, and the public key is publicly published in the DNS.
- The Check: Next, the recipient’s mail server uses the public key from the DNS to verify the digital signature.
- Protection: Ultimately, a valid signature proves two things: the email actually originated from the claimed domain, and the content was not altered since it was signed. Clearly, this prevents phishing attacks that try to inject malicious links mid-transit.
3-DMARC: The Control Tower and Reporter:
DMARC (Domain-based Message Authentication, Reporting, and Conformance) is the essential policy layer. Significantly, it ties SPF and DKIM together.
- Mechanism: The DMARC record is set in DNS. It specifies a policy (
p=) for receiving servers to follow if an email fails both the SPF and DKIM checks. Crucially, it also checks the critical Alignment Check (which ensures the domain in the SPF/DKIM check matches the “From:” header). - The Policy: DMARC applies the domain owner’s stated policy:
p=none(Monitor): The server takes no action, but sends a report (used during setup).p=quarantine: The server sends the failed email to the recipient’s spam folder.p=reject: The server blocks and rejects the email completely.
- Abuse Reporting: Abuse Reporting: Furthermore, DMARC gives the domain owner control over unauthenticated email. Additionally, it provides reports on who is successfully and unsuccessfully trying to use their domain. This allows security teams to respond to spoofing attempts rapidly. To understand how to read these reports, please review our detailed post on (https://domainera.net/glossary/technical-deep-dive-dns-spoofing-cache-poisoning/).
Implementing Your Multi-Layered Defense
In conclusion, by implementing all three protocols, an organization creates a comprehensive defense. Finally, this strategy drastically reduces the success rate of email spoofing and phishing attacks targeting their brand. Make Secure Email Delivery a priority—your customers and partners will certainly appreciate it.
Last modified: December 10, 2025
