What Is Mimecast? A Complete Guide to Email Security, Archiving, and Threat Protection

In today’s threat landscape, email remains both the backbone of business communication and the most common entry point for cyberattacks. From phishing and ransomware to business email compromise (BEC), organizations face constant risks. So, what is Mimecast, and why do thousands of businesses rely on it?

Mimecast is a cloud-based email security, archiving, and cyber resilience platform designed to protect organizations from email-borne threats, data loss, and operational disruption. It combines advanced threat detection, AI-driven analysis, email continuity, and compliance tools into a unified security solution.

This guide explains how Mimecast works, its key features, and why it plays a critical role in modern cybersecurity strategies.

What Is Mimecast and How Does It Work?

Mimecast is a Software-as-a-Service (SaaS) platform that sits between your organization’s email server (such as Microsoft 365 or Google Workspace) and the internet. It acts as a secure gateway, inspecting inbound and outbound emails before they reach users.

Its core functions include:

• Email security and threat protection
• Email archiving and compliance management
• Business continuity and disaster recovery
• Data loss prevention (DLP)
• Human risk management and security awareness

By scanning messages in real time and applying layered defenses, Mimecast prevents malicious emails, suspicious attachments, and harmful links from reaching employees.

Email Security and Threat Protection

Email security is Mimecast’s primary focus. The platform protects against:

• Phishing attacks
• Spear phishing and impersonation attempts
• Malware and ransomware
• Business email compromise (BEC)
• Spam and malicious URLs

Mimecast uses a multi-layered defense model that includes signature-based detection, sandboxing, URL rewriting, attachment scanning, and behavioral analysis. Suspicious files can be detonated in a controlled environment to analyze their behavior before delivery.

This layered approach significantly reduces the risk of compromised accounts and data breaches.

AI-Powered Threat Detection

Artificial intelligence plays a central role in Mimecast’s modern threat protection strategy.

Rather than relying solely on known threat signatures, Mimecast uses machine learning to analyze:

• Email content patterns
• Sender reputation and domain anomalies
• User behavior deviations
• Communication history

This enables the system to detect zero-day attacks and sophisticated social engineering tactics that traditional filters may miss.

AI-driven analysis allows organizations to move from reactive security to proactive threat prevention.

Email Archiving and Compliance

Beyond protection, Mimecast provides robust email archiving solutions.

Organizations are required to retain email records for regulatory, legal, and operational purposes. Mimecast’s cloud archive:

• Automatically stores inbound and outbound emails
• Enables fast search and retrieval
• Supports eDiscovery and litigation holds
• Helps meet regulatory compliance requirements

This is particularly important for industries such as finance, healthcare, legal services, and government agencies, where data retention rules are strict.

By centralizing archived communications, Mimecast improves governance and reduces legal risk.

Business Continuity and Email Resilience

Email downtime can halt operations. Mimecast includes built-in continuity services that ensure employees can continue sending and receiving emails even if the primary email server fails.

In the event of:

• Microsoft 365 outages
• Server disruptions
• Cyber incidents

Mimecast provides temporary mailbox access through its web portal, allowing uninterrupted communication.

This resilience capability strengthens operational stability and disaster recovery planning.

Human Risk Management

Human error remains one of the largest cybersecurity vulnerabilities.

Mimecast addresses this through:

• Security awareness training
• Phishing simulations
• Risk scoring for employees
• Behavioral analytics

By identifying high-risk users and educating employees on evolving threats, organizations can significantly reduce the likelihood of successful phishing attacks.

This focus on human risk transforms security from purely technical protection into a culture-driven defense strategy.

Data Loss Prevention (DLP)

Protecting sensitive data is critical for maintaining compliance and brand reputation.

Mimecast’s data loss prevention tools:

• Monitor outgoing communications
• Detect sensitive information (PII, financial data, confidential records)
• Enforce encryption policies
• Prevent accidental or malicious data leaks

DLP capabilities help organizations comply with regulations such as GDPR, HIPAA, and other data protection standards.

Integration With Microsoft 365 and Other Platforms

Mimecast integrates seamlessly with major email platforms, including:

• Microsoft 365
• Microsoft Outlook
• Google Workspace

It enhances native email security rather than replacing it, adding advanced threat detection and archiving capabilities on top of built-in protections.

Deployment is typically cloud-based, minimizing disruption to existing IT environments.

Industry Recognition and Analyst Validation

Mimecast’s position in the cybersecurity market is supported by recognition from leading industry analyst firms. The company has been named a Leader in recent Gartner Magic Quadrant reports for Email Security Platforms, reflecting Gartner’s evaluation of its ability to execute and completeness of vision. Recognition in multiple Gartner assessments reinforces Mimecast’s credibility as an established and competitive provider in the email security space.

In addition, Mimecast has been evaluated in the Forrester Wave for Email, Messaging, and Collaboration Security Solutions, where it has been recognized as a Strong Performer. Forrester’s analysis highlights Mimecast’s strengths in threat intelligence, human risk management, and integration capabilities.

Inclusion in both Gartner and Forrester research reports demonstrates that Mimecast is consistently assessed among the leading vendors in enterprise email security and cyber resilience.

Partner Network and Ecosystem Collaboration

Mimecast operates within a broad global partner network designed to enhance deployment efficiency and long-term scalability. Through strategic partners, including managed service providers, resellers, and technology vendors, Mimecast ensures organizations can tailor solutions to their specific security environments.

This partner-driven model strengthens ecosystem-wide collaboration, allowing security teams to integrate Mimecast with existing SIEM tools, endpoint protection systems, and identity platforms. Deep integration with Microsoft 365, cloud environments, and third-party security frameworks improves operational flexibility while maintaining centralized visibility.

By working closely with certified partners, organizations can accelerate deployment, streamline configuration, and reduce operational complexity.

Insider Threat Mitigation and Shadow IT Visibility

While external attacks dominate headlines, insider risk remains a critical concern. Mimecast provides advanced tools for insider threat detection and mitigation by analyzing anomalous behavior patterns and communication flows.

Its behavioral analytics engine uses contextual signals and intelligence capabilities to identify potential misuse of credentials, suspicious forwarding rules, or unusual data access. This allows organizations to proactively detect and reduce insider-driven vulnerabilities before they escalate.

Additionally, Mimecast helps identify risks associated with shadow IT activity, where unauthorized applications or unsanctioned communication channels may expose sensitive data. By monitoring outbound traffic and policy violations, organizations can reduce data leakage and strengthen governance frameworks.

Through continuous monitoring and structured training programs, security teams can reduce human risk while reinforcing awareness across the workforce.

Governance, Flexibility, and Secure Deployment

Effective cybersecurity requires structured governance policies that align with regulatory requirements and business objectives. Mimecast supports compliance-driven environments by enabling centralized policy management, audit trails, and reporting tools.

Its cloud-native architecture allows flexible deployment models, whether organizations require hybrid, multi-cloud, or fully cloud-based protection. This architectural flexibility ensures businesses can scale security infrastructure without disrupting existing operations.

With modular solutions spanning email security, archiving, continuity, and insider risk management, organizations gain a cohesive security framework without unnecessary complexity.

Frequently Asked Questions (FAQ)

What is Mimecast used for?

Mimecast is used to secure business email systems against phishing, malware, ransomware, and impersonation attacks. It also provides email archiving, continuity services, data loss prevention, and employee risk management tools.

Why am I receiving a Mimecast message?

You may receive a Mimecast notification if the organization you’re communicating with uses Mimecast to filter and scan emails. Messages may be held or flagged if they trigger security checks.

Is Mimecast part of Microsoft Outlook?

No. Mimecast is not part of Outlook, but it integrates with Microsoft 365 and Outlook to provide enhanced email security and archiving features.

Is Mimecast safe and reliable?

Mimecast is widely regarded as a secure and reliable email security provider. It uses multi-layered protection, AI-driven detection, and compliance tools to safeguard business communications.

Final Thoughts

So, what is Mimecast? It is far more than a spam filter. Mimecast is a comprehensive email security, archiving, and threat protection platform designed to help organizations defend against modern cyber threats while maintaining compliance and operational resilience.

By combining AI-powered detection, advanced threat protection, email continuity, and human risk management, Mimecast delivers a holistic approach to cyber resilience. For businesses that depend on secure digital communication, it represents a strategic layer of defense in an increasingly complex threat environment.