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How does the Zero Trust model protect your inbox?

Tshedimoso Makhene December 10, 2025

Cybersecurity

How does the Zero Trust model protect your inbox?

The status of email security in healthcare is characterized by high risk, rising threat sophistication, critical infrastructure failures, and a dangerous misalignment between IT confidence and actual vulnerability. As Paubox notes, email remains the single largest vector for cyberattacks in the healthcare sector and is consistently cited as the weakest security link.

The introduction of the Zero Trust security model has been important in transforming this by protecting inboxes. According to the study A Zero Trust Email Security Framework for Governments, Smes, and Cloud Providers, “In the case of email, Zero Trust may be used as an effective method of increasing the level of security. It authenticates senders and recipients, examines the contents of the message and attachment, tracks user activity, and uses access controls to block outbound traffic according to the context of the risk. In a case where a user may not be following his/her usual habit, like sending bulk emails out of their working hours, the system can automatically flag it or prevent it.”

Dangers facing email

According to the article, Email in healthcare: pros, cons and efficient use, by Stephan Ginn, “In 2021 the total number of business and consumer emails sent and received each day worldwide was forecast as more than 319 billion and predicted to grow to over 376 billion by the end of 2025. The healthcare sector was initially more cautious about the adoption of email than other sectors, but email is now a primary method of correspondence between healthcare professionals.” As email becomes more deeply embedded in clinical workflows, used for scheduling, care coordination, patient communication, and document sharing, it also becomes a much larger and more attractive attack surface.

This widespread use of email as a communication tool in healthcare has introduced a platform that cybercriminals can exploit. As Paubox notes, between January 1, 2024, and January 31, 2025, 180 healthcare organizations reported email-related security breaches to the HHS Office for Civil Rights (OCR). Furthermore, the company found that in the first half of 2025 alone, January through July, 107 email-related breaches were reported to HHS, putting the year on track to match or exceed the 2024 total.

These statistics show that email is one of the largest and fastest-growing cybersecurity liabilities in healthcare. High volumes, sensitive information, and human error create ideal conditions for phishing, credential theft, business email compromise, and data exfiltration. Without stronger, modern protections like the Zero Trust security model, organizations remain exposed to attacks that can disrupt care, compromise patient data, and trigger costly regulatory penalties.

What is the Zero Trust model?

According to IBM, “Zero trust is a security strategy for modern multicloud networks. Instead of focusing on the network perimeter, a zero trust security model enforces security policies for each individual connection between users, devices, applications and data.” This model works on the principle of “nothing, neither an inside nor an outsider, should ever be trustworthy in default,” notes the study A Zero Trust Email Security Framework for Governments, Smes, and Cloud Providers. This means that instead of assuming a user or device is safe because they authenticated once or connected from a known location, Zero Trust treats each interaction as potentially malicious until proven otherwise. This includes:

Every email request
Every attempt to download an attachment
Every unusual login
Every outbound email leaving the organization
Every sudden behavioral shift

Zero Trust uses a combination of identity verification, device checks, behavioral analytics, continuous monitoring, and context-based access controls to ensure that only safe, verified actions are allowed.

How Zero Trust strengthens inbox security

Zero Trust transforms inbox security by applying layers of verification, monitoring, and real-time enforcement. As the study A Zero Trust Email Security Framework for Governments, Smes, and Cloud Providers notes, “With Zero Trust, real-time solutions to compute sender identity, privilege of the recipient, contents of an email, and behavior of the user will be generated under email security. Case studies related to finance and medical establishments have been able toportray that going Zero Trust will lead to a significant reduction of data breaches.”

Zero Trust protecting your inbox

According to Google, the Zero Trust security model protects your inbox by:

“Least-privilege access: Users are granted the minimum level of access necessary to perform their tasks. By limiting user permissions, organisations can reduce the risk and impact of data breaches and unauthorised access to sensitive information.
Context-aware access: Access decisions are based on a variety of factors, such as device type, OS version, location and the sensitivity of the data being accessed. The same users who may otherwise have access to data using a specific device and location, for example, may not have access using a different device.
Continuous evaluation: User and device identities are continuously verified throughout each session. This involves continuous monitoring of user activity, as well as the use of advanced analytics and automation to identify and mitigate potential risks.”

Developing a Zero Trust security framework

According to the study A Zero Trust Email Security Framework for Governments, SMEs, and Cloud Providers, the design of a Zero Trust security model uses a systematic and six-phase design model. This mitigates sector-related risks and follows the core principles of Zero Trust security. The steps include:

Determining email threat vectors: What attack vectors are common in your organization? Phishing, spoofing, malware through attachment, and business email compromise (BEC) are all examples of attack vectors.
Gathering sector/organizational-specific security information: What vulnerabilities are most common in your sector or industry?
Mapping out vulnerabilities and risk patterns: What vulnerabilities lead to the biggest risk? As the study notes, “Vulnerabilities that are most important were placed against the threat vectors.”
Using Zero Trust principles: “Zero Trust principles offered a solution to the identified risks since the risks that were depicted on the maps were mitigated by least privilege access, continuous authentication, device posture validation, and adaptive policy enforcement.”
Designing a framework by sector/organization: A specific Zero Trust strategy offers better protection. For example, “Cloud vendors would have used micro-segmentation and multi-tenant isolation, where SMEs would have made more use of lightweight AI-powered, multi-factor authentication (MFA) gateways.”
Following industry standards: The framework should then be compared to the industry-standard cybersecurity frameworks so that it is “compatible with the national and international best practices.”

See also: Zero-trust architecture in healthcare cybersecurity

Implementing Zero Trust security

To implement Zero Trust, the study suggests the following:

“Identity verification: Verifies that those users and devices accessing the email are indeed authenticated through the use of multi-factor authentication and alerts on the context.
Least privilege access: Prevents sending, forwarding, and downloading of sensitive information unless permitted to do so explicitly.
Continuous monitoring: This type monitors the behaviorof users in real-time with the help of analytics and AI technology, detecting factors such as a suspicious origin of login or IP addresses or the unusual amount of emails.
Data encryption: Encrypts the contents and the metadata in order to deny interception and tampering.”

Paubox’s approach to Zero Trust

Paubox applies Zero Trust principles by assuming no email, user, or device is trustworthy by default. Instead of relying only on traditional filters, Paubox builds identity verification, behavioral monitoring, and continuous risk assessment into every stage of email communication.

At the core of this approach is identity-centric security. Paubox validates sender identity, domain authentication (SPF, DKIM, DMARC), and contextual risk factors to stop spoofing, phishing, and Business Email Compromise before messages reach the inbox. Paubox also uses behavioral analytics to detect unusual activity, such as abnormal sending patterns, logins from unfamiliar locations, or attempts to forward sensitive data. When something looks suspicious, the system can automatically block, flag, or quarantine the email, reducing the chance of account takeover or data loss.

Since Zero Trust applies to all directions of communication, Paubox evaluates outbound email as well. It monitors for risky behaviors, PHI exposure, and unauthorized data sharing, helping prevent both accidental and malicious leaks.

Paubox delivers secure, encrypted email directly to inboxes, avoiding portals and extra logins, while maintaining strong behind-the-scenes identity controls. This reduces friction for users without weakening security.

Overall, Paubox’s approach reinforces the core Zero Trust principle of “never trust, always verify,” creating a dynamic and adaptive layer of protection around both inbound and outbound email activity.

See also:

FAQS

Why is email such a common target for cyberattacks?

Email is widely used, easy to spoof, and often contains sensitive information. Attackers exploit human error, send convincing phishing messages, steal login credentials, and try to infiltrate organizations by compromising inboxes. Its ubiquity makes it one of the easiest ways for cybercriminals to gain access to internal systems.

Does Zero Trust protect against compromised accounts?

Yes. Even if an attacker steals a password, Zero Trust uses risk-based authentication, MFA, device posture checks, and behavioral monitoring to detect unusual activity. Suspicious login attempts are blocked, and unusual email-sending behavior is automatically restricted.