The Best DLP Solutions and Platforms for Email Security

What Is an Email Data Loss Prevention (DLP) Solution?

An email data loss prevention (DLP) solution helps organizations prevent sensitive information from leaving through email. It looks at outbound messages to identify confidential information, regulated data, risky recipients, unusual forwarding behavior and other conditions that might indicate accidental exposure or exfiltration.

Email DLP also needs to account for how people actually work. Employees move quickly, rely on autocomplete, forward messages across teams and share files in ways that are often routine until something goes wrong. Many newer platforms supplement policy-based controls with behavioral analysis that learns normal communication patterns.

The best email DLP solutions combine detection with response so users correct mistakes without breaking their workflow.

Why Email Security Platforms Matter for DLP

Users send attachments, reply to external recipients, copy the wrong person or forward information without realizing the impact. Many outbound data exposure incidents stem from routine user mistakes rather than malicious intent.

Traditional approaches like a secure email gateway may still be useful for blocking known spam or malware. However, secure email gateways typically focus on filtering threats and enforcing policy rather than evaluating user behavior. Modern email threats are increasingly contextual, and outbound risk is often invisible until a message is already in motion.

That matters even more in Microsoft 365-heavy environments, where email is tightly connected to daily collaboration and AI-assisted workflows. According to The Register, recent Copilot behavior showed that even labeled confidential emails can surface in ways buyers may not expect.

Best Email Security Platforms and DLP Solutions to Consider

Choosing an email security and DLP platform requires balancing strong data protection with minimal disruption to everyday workflows. Most platforms take one of two approaches: gateway-based tools that rely on policy enforcement at the perimeter, or cloud-native platforms that analyze activity directly within the email environment.

Below is a look at how leading platforms approach outbound protection, user guidance, and data security.

1. KnowBe4 Prevent™

KnowBe4 Prevent focuses on reducing human-driven email risk before a message is sent. The platform operates directly within Microsoft 365 and Outlook through client add-ins. Rather than relying primarily on gateway routing or regex-based policies, KnowBe4 Prevent uses behavioral AI and machine learning to analyze communication patterns, recipients, message text and attachments in real time.

This allows the system to identify anomalies such as lookalike domains, autocomplete errors and unauthorized data sharing, then stop outbound data loss.By shifting enforcement to the client layer, KnowBe4 Prevent delivers contextual, real-time user coaching when an anomaly is detected.

2. Proofpoint

Proofpoint takes a hybrid approach to outbound DLP that combines gateway-based controls with behavioral analysis tools. Outbound compliance and regex-based scanning are enforced at the perimeter, where alerts are routed through quarantine or encryption. For behavioral detection, Proofpoint supplements its policy controls with adaptive email DLP capabilities and DSPM technology.

This combination identifies misdirected emails and traces data lineage across hybrid, cloud and on-premises environments.

However, Proofpoint’s core policy DLP and encryption capabilities are not sold standalone and require higher product tiers.

3. Mimecast

Mimecast handles outbound email security and DLP primarily through its Cloud Gateway architecture, relying on policy-based DLP rules, encryption and secure messaging workflows. To deliver broader outbound protection and secure content delivery, organizations often need both Mimecast’s Cloud Gateway and its separate Secure Messaging module.

This approach focuses on perimeter-level policy enforcement and data routing rather than real-time behavioral guidance in the email client while a message is being composed. KnowBe4 instead emphasizes in-client detection, user coaching and encryption within a single platform.

4. Abnormal

Abnormal Security focuses on outbound protection through its Misdirected Email Prevention module. The platform analyzes recipient context, communication history and metadata to identify unusual sending activity.

However, Abnormal does not offer a full standalone outbound email DLP platform. It lacks native policy-based compliance controls, sensitive content filtering and native email encryption or secure file transfer capabilities, so organizations often need third-party tools to cover broader outbound data governance.

5. Check Point

Check Point manages outbound DLP for email and collaboration applications primarily through traditional, rules-based controls. Its architecture relies on static rules and predefined regex expressions to identify sensitive data before it leaves the organization.

Because this approach evaluates content against fixed criteria rather than user intent or relationship context, it often requires ongoing tuning to stay accurate. It can also create gaps in coverage for intent-driven mistakes and lead to more false positives in complex communication flows.

KnowBe4 places greater emphasis on behavioral analysis and automated detection, reducing reliance on manual rule tuning.

6. Microsoft

Microsoft Defender for Office 365 is primarily optimized for inbound threat detection. For stronger outbound DLP and behavioral risk detection, organizations need Microsoft Purview, which often requires higher-tier licensing such as E5 Compliance.

Purview provides data protection, but deployment can depend on static, policy-based rules, manual data labeling and complex configuration across multiple portals. Its controls also tend to lack focus on real-time coaching during email composition.

KnowBe4 extends outbound protection directly within Microsoft 365 and Outlook through client add-ins that provide behavioral analysis and real-time user guidance.

Key Features to Look for in an Email Security Platform for DLP

A strong DLP platform does more than inspect text for keywords. It understands the context around a message, recognizes abnormal behavior and corrects risky actions before they cause damage. Key features to look for include:

• Outbound email threat detection
• Sensitive data and attachment analysis
• Adaptive policy controls
• Real-time coaching and user prompts
• Encryption and granular access controls
• Human risk visibility
• Integration with the existing security stack

Outbound Email Threat Detection

Outbound detection examines messages before they leave the organization. It reviews recipients, domains, attachment behavior, sensitive content and unusual send patterns to identify both mistakes and intentional exfiltration.

Sensitive Data and Attachment Analysis

A capable DLP platform inspects message text and attachments for regulated data, confidential information, customer records, financial details, intellectual property and custom patterns tied to the business.

In many organizations, the attachment is where the real risk lives. If the platform cannot analyze it well, it is missing a major exposure point.

Adaptive Policy Controls

Modern email DLP should adapt to context, user behavior and risk level rather than treating every employee, file type and recipient the same way. Adaptive policy controls reduce false positives and avoid slowing legitimate sends.

Real-Time Coaching and User Prompts

One of the most important shifts in email security is the move from pure blocking to in-the-moment guidance. Contextual prompts and coaching give users a chance to reconsider a send, correct a recipient or rethink an attachment before the email goes out. That is especially valuable when the issue is human error rather than malicious intent.

Encryption and Granular Access Controls

When sensitive information does need to be shared, encryption and access controls reduce exposure. Useful features can include:

• Restricted viewing
• Download limits
• Revocable access and controls that limit copy and paste.

These capabilities are useful when the business has to share sensitive content but still wants to govern what happens after the file or message is shared.

Human Risk Visibility

DLP is far more useful when it helps teams understand who is creating risk and why. Visibility into repeated behaviors, high-risk roles like finance or legal, and common misdelivery patterns lets security teams tune policies and focus training where it will matter most.

Integration With the Existing Security Stack

The most effective platforms fit into your organization’s broader security ecosystem and connect with identity, collaboration and response workflows. In Microsoft 365 environments especially, native integration makes the difference between a tool that gets adopted and one that creates overhead.

Questions to Consider When Choosing a DLP Solution for Email Security

Before selecting a platform, security teams should pressure-test the product against the way their users actually work.

• Does the platform focus on email DLP, or only general DLP?
• Can it detect sensitive data in outbound emails and attachments?
• Does it help prevent misdirected emails and risky external sends?
• Can it protect sensitive data after an email is sent?
• Does it offer encryption and access controls?
• Does it coach users in real time?
• Does it provide visibility into risky user behavior?
• Can it reduce false positives and user friction?
• Does it integrate with your existing security stack?
• Can it support compliance and reporting needs?

Strengthen Email DLP and Data Protection With KnowBe4 Prevent

Email DLP is increasingly about reducing human error. The most effective platforms help security teams identify risky behavior, prevent accidental exposure and coach users before sensitive data leaves the organization.

KnowBe4 Prevent is built for that shift. Instead of forcing every send through the same rigid policy path, it helps employees make better decisions when the stakes are highest. It combines behavioral AI, misdirected email prevention, real-time Microsoft 365 alerts, and contextual user coaching to reduce outbound email risk at the point of action.

Explore how KnowBe4 Prevent can reduce outbound email data loss.