--- title: "Building a zero-trust security model for emails | DuoCircle" description: "Building a zero-trust security model for emails." image: "https://www.duocircle.com/images/og-default.png" canonical: "https://www.duocircle.com/blog/email-security/building-a-zero-trust-security-model-for-emails/" --- Quick Answer Zero-trust email security inverts the default assumption: instead of trusting messages by location or sender pattern, every email is verified before it reaches the inbox. Verizon's 2023 DBIR puts 75 to 91 percent of targeted attacks as starting with email, which is why this model has displaced perimeter-based defenses. The four working components: email authentication (SPF, DKIM, DMARC) so the sender's domain is verified by cryptographic signature and DNS policy, two-factor authentication so a stolen password alone doesn't grant mailbox access, password management so credentials are unique and stored encrypted, and email encryption so message content is unreadable in transit if intercepted. SPF lists authorized sending IPs and applies softfail or hardfail at the receiver. DKIM signs each message with a private key the receiver verifies against the public key in DNS. DMARC ties the two together with a policy (none, quarantine, reject) and aggregate reporting so you see who is spoofing your domain. Skip any of the four and the model collapses back to implicit trust. Building a zero-trust security model for emails Your browser does not support the audio element. [ Download episode](https://media.mailhop.org/duocircle/images/2024/12/Building-a-zero-trust-security-model-for-emails.mp3) Share [ ](https://www.linkedin.com/sharing/share-offsite/?url=undefined%2Fblog%2Femail-security%2Fbuilding-a-zero-trust-security-model-for-emails%2F "Share on LinkedIn") [ ](https://twitter.com/intent/tweet?text=Building%20a%20zero-trust%20security%20model%20for%20emails&url=undefined%2Fblog%2Femail-security%2Fbuilding-a-zero-trust-security-model-for-emails%2F "Share on X/Twitter") [ ](https://www.facebook.com/sharer/sharer.php?u=undefined%2Fblog%2Femail-security%2Fbuilding-a-zero-trust-security-model-for-emails%2F "Share on Facebook") [ ](https://reddit.com/submit?url=undefined%2Fblog%2Femail-security%2Fbuilding-a-zero-trust-security-model-for-emails%2F&title=Building%20a%20zero-trust%20security%20model%20for%20emails "Share on Reddit") [ ](mailto:?subject=Building%20a%20zero-trust%20security%20model%20for%20emails&body=Check out this article: undefined%2Fblog%2Femail-security%2Fbuilding-a-zero-trust-security-model-for-emails%2F "Share via Email") ![security model for emails](https://media.mailhop.org/duocircle/images/2024/12/spf-permerror-3095.jpg) According to [Verizon’s 2023 Data Breach Investigations Report](https://www.verizon.com/business/resources/reports/dbir/), somewhere between **75% and 91%** of targeted cyberattacks start with an email. Considering that such statistics surface in the news every day, organizations are trying to keep up with the growing number of sophisticated cyberattacks. Email is one of the most exploited vectors for phishing and [ransomware attacks](https://www.cyberdaily.au/security/11478-us-treasury-department-sanctions-chinese-firm-over-ransomware-attacks). [Traditional security measures and technologies are evidently failing to ward off new-age cyberattacks](https://guardiandigital.com/resources/blog/why-traditional-security-solutions-arent-stopping-ransomware); that’s why the latest solutions, like zero-trust security models, are emerging as robust alternatives. ## What is a zero-trust security model for emails? Zero-trust security is a new-age cybersecurity concept that is basically the opposite of the ‘**trust but verify’ approach**. In simpler words, the zero-trust model focuses on allowing [legitimate emails](https://www.trendmicro.com/vinfo/us/security/definition/legitimate-bulk-emails) rather than trying to identify and block illegitimate ones. This [cybersecurity](/) approach assumes no email or sender is inherently trustworthy, regardless of origin. That’s why it continuously verifies all the aspects of email interactions, including sender identity, attachments, and links. All this is done using advanced authentication, encryption, and monitoring technologies. ### Why zero-trust security model for emails? Recent research shows that [86.5% of organizations](https://www.csoonline.com/article/1249027/9-in-10-organizations-have-embraced-zero-trust-security-globally.html#:~:text=The%20report%2C%20based%20on%20a,have%20mature%20deployments%20in%20place.) have implemented some aspects of [zero-trust security](https://www.techtarget.com/searchsecurity/definition/zero-trust-model-zero-trust-network), yet only 2% have reached full maturity. This disparity speaks volumes about how many organizations still do not focus on shielding email systems and lack the **funds and experts** to work on this. _By adopting the zero-trust model, email systems are no longer assumed to be secure based solely on their location within a network_. Instead, every interaction, whether a **login, message, or attachment**, is scrutinized, authenticated, and monitored in real-time. [![email security model ](https://media.mailhop.org/duocircle/images/2024/12/spf-record-generator-3285.jpg)](https://media.mailhop.org/duocircle/images/2024/12/spf-record-generator-3285.jpg) ## Four critical features of a robust zero-trust security model for emails An efficient [email security](/content/email-security-services) system inherits these **four important features**\- ### Email authentication The foremost step is to provide a way to **verify the authenticity** of the email sender. This helps to determine whether a malicious, unauthorized sender sent the email. This is done using [SPF](/resources/what-is-spf), DKIM, and DMARC. ### Two-factor authentication [Two-factor authentication (2FA)](https://thehackernews.com/2024/05/google-simplifies-2-factor.html) makes your email more secure by adding **extra protection** beyond just a password. This additional layer makes it harder for hackers to access your email, even if they manage to guess your password. 2FA works using three types of checks: - **Knowledge**: Something you know, like an **additional password**. - **Possession**: Something you have, such as your phone or a security device that generates a code (like an [One time password](https://www.techtarget.com/searchsecurity/definition/one-time-password-OTP)). - **Inherence**: Something unique to you, like your fingerprint, face, or eye patterns, verified using biometric scanners or facial recognition. ### Password management Password management tools are essential for securely storing and organizing your passwords. These tools generate [strong, unique passwords](https://cybernews.com/best-password-managers/how-to-create-a-strong-password/) for each account, reducing the risk of reuse and vulnerability. They encrypt your credentials, keeping them safe from hackers, and automatically fill in login details, saving time and effort. By using a single master password to access all stored passwords, a password manager **simplifies account management** while enhancing security. ### Email encryption [Email encryption](https://www.fortinet.com/resources/cyberglossary/email-encryption) stops unauthorized people from reading your email while it’s being sent. It works by turning the message into unreadable text **using special characters** so only the intended recipient can read it. Even if a [hacker intercepts](https://www.nbcnews.com/tech/security/us-officials-urge-americans-use-encrypted-apps-cyberattack-rcna182694) the email, they won’t be able to understand it. ## Building a zero-trust security model for your organization’s email infrastructure Zero-trust is built on **three authentication protocols**, SPF, DKIM, and DMARC. Here’s how each of these works- ### SPF SPF is the primitive [email authentication](/resources/email-authentication) protocol in which the domain owner has to specify email servers officially authorized to send emails on behalf of the organization. Emails sent from servers not listed in the [SPF record](/content/spf-records) fail authentication checks. In the same record, you must specify how **recipients’ mailboxes** should handle emails that fail the check. You can choose between ‘[SoftFail’ or ‘HardFail](https://support.cpanel.net/hc/en-us/articles/360051455074-What-is-the-difference-between-an-SPF-hard-fail-and-soft-fail).’ With SoftFail, unauthorized emails sent from your domain are [marked as spam](https://www.infosecurity-magazine.com/news/black-friday-spam-emails-scams/) by the recipients’ mailboxes. With HardFail, these emails are outright rejected and [bounced back](https://www.activecampaign.com/glossary/bounced-email) to the sender. ### DKIM [DKIM](/resources/what-is-dkim) is a security protocol that uses cryptography to confirm that emails from your domain remain unchanged during transmission. It attaches a digital signature to the [email header](https://proton.me/blog/what-are-email-headers), which is generated with your [private key](https://www.investopedia.com/terms/p/private-key.asp). The matching public key, stored in your domain’s DNS, allows receiving servers to **verify the email’s legitimacy** and ensure its content hasn’t been tampered with. ### DMARC _DMARC ensures that SPF and DKIM authentication results match the sender’s domain in the email’s ‘From’ header_. Domain owners set up a [DMARC record](/resources/create-dmarc-records) in their DNS, defining one of three actions: none (**monitor email activity** without intervention), quarantine (send [suspicious emails](https://www.darkreading.com/cloud-security/new-dmarc-data-shows-75-increase-in-suspicious-emails-hitting-inboxes) to spam), or reject (block unauthorized emails). DMARC also generates reports to help domain owners track and enhance their email security. Once you are done implementing SPF, DKIM, and [DMARC](/resources/what-is-dmarc), start incorporating the following- ### Establish a baseline of security measures Establishing a **strong foundation of security measures** involves implementing essential technologies to protect emails and their contents at every stage. - Encryption ensures that email data remains private and unreadable to unauthorized parties during transmission. - Malware detection helps identify and block [malicious attachments](https://www.computerweekly.com/news/366605874/Phishing-links-becoming-bigger-threat-than-email-attachments) or links before they can harm the system. - [Data Loss Prevention (DLP)](https://www.ibm.com/topics/data-loss-prevention) tools monitor and prevent sensitive information from being accidentally or intentionally leaked through email. - Lastly, [Secure Email Gateways (SEGs)](/email-hosting/understanding-the-relevance-of-secure-email-gateways-segs/) act as a barrier, scanning incoming and outgoing emails for threats, spam, and **compliance violations**. Together, these technologies provide a **robust starting point** for building a Zero Trust email security framework, minimizing vulnerabilities while supporting safe and reliable communication. [![benefits of Data Loss Prevention](https://media.mailhop.org/duocircle/images/2024/12/spf-validator-3.jpg)](https://media.mailhop.org/duocircle/images/2024/12/spf-validator-3.jpg) ### Map the transaction flow The next thing you need to do is map all the transaction flows between **internal and external users** so that you can determine what types of access users require and which ones to restrict them from. ### Architect a zero-trust network Architecting a zero-trust network starts with an assumption that threat actors might already have access to the network and requires strict verification for every request. It’s suggested that you mindfully divide the entire [email infrastructure](https://www.voilanorbert.com/blog/email-infrastructure/) into **isolated zones or segments** to enhance security by limiting the scope of access and containing potential breaches. You can segment it based on internal and external traffic zones, zones for **high-value systems**, or by segmenting email gateways and security tools. ## Final thoughts _Implementing a zero-trust security model for emails isn’t a one-time job_. Once you have built it, you have to **constantly monitor** it for maintenance. If you want to get started with this model but don’t have DMARC in place, then [allow us to help you out](/contact). ## Topics cyber securityDKIMDMARCemail securitySecurityspfSPF record ![Brad Slavin](https://media.mailhop.org/dmarcreport/images/team/brad-slavin.jpg) Brad Slavin General Manager General Manager at DuoCircle. Product strategy and commercial lead across the email security portfolio. ## Secure your email infrastructure Protect, authenticate, and deliver. Contact our team to find the right solution. [Contact Sales](/contact/) [Explore Products](/products/) ## Related Articles [ Email Security 8m What are the most important email security protocols, and how do they protect your communications? Feb 13, 2025 ](/blog/email-security/important-email-security-protocols-and-how-they-protect-communications/)[ Email Security 12m DMARC, SPF, and DKIM in 2026: Why Email Authentication Is Now a Regulatory Requirement, Not Just a Best Practice Apr 29, 2026 ](/blog/dmarc-spf-dkim-2026-email-authentication-regulatory-requirement-best-practice/)[ Email Security 4m A practical guide on checking your email health Dec 26, 2025 ](/blog/email-security/a-practical-guide-on-checking-your-email-health/)[ Email Security 8m Best practices to make Privileged Account and Session Management a breeze Jan 7, 2025 ](/blog/email-security/best-practices-for-simplifying-privileged-account-and-session-management/) ```json {"@context":"https://schema.org","@type":"Organization","name":"DuoCircle LLC","url":"https://www.duocircle.com","logo":{"@type":"ImageObject","url":"https://www.duocircle.com/images/duocircle-logo.png"},"description":"DuoCircle is a portfolio of specialized email products covering protection, authentication, delivery, and routing. 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