Email remains one of the most important communication channels in a law firm. Attorneys use it to exchange documents, receive payment instructions, communicate with clients, coordinate matters, and access cloud services. That also makes the inbox an attractive entry point for phishing, credential theft, malware, impersonation, and business email compromise.
Modern email security platforms go beyond spam filtering. They can analyze sender behavior, inspect links and attachments, detect executive or vendor impersonation, identify account takeover, remove malicious messages after delivery, and automate investigation and response.
What Should a Law Firm Look for in Email Security?
Important capabilities include:
Phishing and spear phishing detection
Business email compromise protection
Executive and vendor impersonation detection
Malicious link and attachment protection
Account takeover detection
Post delivery threat removal
Microsoft 365 integration
User reporting and investigation workflows
Security awareness or phishing simulation options
Email authentication and domain protection
Law firms should also consider deployment model. Traditional secure email gateways inspect mail before delivery, while newer API based platforms connect directly to Microsoft 365 or Google Workspace and can analyze messages and user behavior inside the cloud environment.
7 Email Security Vendors for Law Firms to Consider
1. Proofpoint Core Email Protection
Best for: Large firms wanting enterprise grade email security
Proofpoint Core Email Protection provides phishing, business email compromise, ransomware, account takeover, malware, and impersonation protection for Microsoft 365 and Google environments.
Proofpoint supports both API and secure email gateway deployment models. Its platform combines threat intelligence, machine learning, behavioral analysis, URL inspection, attachment analysis, and automated response.
For large law firms with dedicated security teams, Proofpoint is particularly strong when email protection needs to connect with broader data loss prevention, security awareness, threat investigation, and Microsoft 365 security programs.
2. Mimecast Advanced Email Security
Best for: Firms wanting layered email security and continuity
Mimecast Advanced Email Security protects Microsoft 365, Google Workspace, and on premises email environments against phishing, business email compromise, ransomware, zero day exploits, malicious URLs, and attachments.
Mimecast offers both gateway based and cloud integrated approaches. Its broader platform also includes DMARC management, collaboration security, data protection, awareness training, archiving, and email continuity.
That wider email focused portfolio can be useful to firms that want security, continuity, and compliance related capabilities from the same provider.
3. Abnormal AI
Best for: Firms focused on business email compromise and behavioral attacks
Abnormal AI for Microsoft 365 takes an API based approach to cloud email security. Instead of relying primarily on known malicious signatures, it analyzes normal communication patterns and relationships to identify unusual behavior.
The platform targets phishing, account takeover, vendor fraud, impersonation, and business email compromise. It can also extend protection into Microsoft Teams and monitor Microsoft 365 configuration risks.
Abnormal is especially relevant for firms concerned about convincing social engineering attacks that contain no obvious malware or malicious attachment.
4. Microsoft Defender for Office 365
Best for: Microsoft 365 focused law firms
Microsoft Defender for Office 365 provides Microsoft native protection against phishing, malicious links, dangerous attachments, impersonation, malware, and other email based threats.
Safe Links checks URLs, while Safe Attachments analyzes potentially dangerous files in a protected environment. Higher tiers add investigation, automated response, threat hunting, campaign views, and attack simulation training.
A significant 2026 change is that Defender for Office 365 Plan 1 became included with Office 365 E3 and Microsoft 365 E3 on July 1, 2026. Firms already paying for Microsoft licenses should therefore review what protection they already own before adding another email security platform.
5. Barracuda Integrated Email Protection
Best for: Small and midsize firms wanting automated protection
Barracuda Integrated Email Protection is an API based service for Microsoft 365 and Google Workspace that launched in 2026.
It provides impersonation and account takeover detection, automated post delivery remediation, domain fraud protection, incident response workflows, and AI based threat analysis. Because it connects through API, deployment does not require changing mail flow or MX records.
Barracuda can be attractive to firms with smaller security teams that want automated detection and cleanup without operating a complicated enterprise email security environment.
6. Check Point Email Security
Best for: Firms wanting email and collaboration protection together
Check Point Email Security protects Microsoft 365 and Gmail against phishing, account takeover, malicious URLs, malware, and impersonation. Higher packages add data loss prevention and protection for collaboration platforms such as Teams, Slack, SharePoint, OneDrive, Dropbox, and Box.
The product was previously called Harmony Email & Collaboration and was renamed Check Point Email Security in March 2026.
For law firms where attorneys increasingly work through Teams and other collaboration applications alongside email, protecting multiple communication channels through one security platform can be useful.
7. IRONSCALES Email Protect
Best for: Firms wanting AI driven phishing detection with simple deployment
IRONSCALES Email Protect is an integrated cloud email security platform that connects with Microsoft 365 and Google Workspace without requiring changes to MX records.
It focuses on phishing, business email compromise, VIP impersonation, malicious links and files, account takeover, and automated threat remediation. Higher tiers add email encryption, data loss prevention, Microsoft Teams protection, security awareness training, and phishing simulations.
IRONSCALES may fit small and midsize firms that want a cloud native email security layer with a high degree of automated investigation and remediation.
Which Email Security Tool Is Best for Your Law Firm?
Proofpoint and Mimecast are strong candidates for larger firms that need broad enterprise email security and supporting capabilities. Abnormal AI stands out for behavioral analysis and sophisticated social engineering attacks, while Microsoft Defender is the logical first option to assess for firms already standardized on Microsoft 365.
Barracuda and IRONSCALES can be attractive to smaller security teams because of straightforward API deployment and automation. Check Point deserves consideration when email protection needs to extend into Teams, SharePoint, OneDrive, and other collaboration applications.
Before selecting a vendor, firms should review their Microsoft 365 licensing, existing spam and malware protection, DMARC configuration, security awareness program, incident response process, and responsibility for investigating user reported phishing.
Where MIRA and MATTEROOM Fit
Email security protects communication channels and user accounts; MIRA works inside Microsoft Teams and fits alongside Microsoft 365 security controls that protect the surrounding work environment. MATTEROOM adds secure legal operations with multifactor authentication, encryption, and single tenant architecture while email security vendors protect the firm's messaging layer.
Frequently Asked Questions
Does Microsoft 365 already include email security?
Yes. Microsoft 365 includes baseline email protection, and some licenses include Microsoft Defender for Office 365. Firms should understand their current licensing and configuration before purchasing additional protection.
What is business email compromise?
Business email compromise, or BEC, is a social engineering attack in which an attacker impersonates a trusted executive, employee, client, or vendor to manipulate the recipient into sending money, credentials, or sensitive information.
What is the difference between a secure email gateway and API based email security?
A secure email gateway typically inspects messages as they travel through the mail flow. API based security connects directly to a cloud email platform and can inspect mailbox activity, user relationships, and messages without changing MX records.
Should law firms provide phishing awareness training?
Yes. Technology can block many attacks, but employees still need to recognize suspicious requests, unusual payment instructions, credential harvesting, and impersonation attempts.
