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🚀 Executive Summary

TL;DR: Traditional email security gateways like Proofpoint are struggling against modern sophisticated phishing and Business Email Compromise (BEC) attacks, leading to increased administrative overhead and poor cloud integration. Organizations can address these challenges by evaluating modern alternatives such as Mimecast for a comprehensive SEG replacement, Abnormal Security for an API-first behavioral AI approach, or Microsoft Defender for Office 365 for native cloud platform integration.

🎯 Key Takeaways

Traditional Secure Email Gateways (SEGs) often fail to detect sophisticated, socially-engineered attacks like BEC and credential harvesting due to their reliance on signature-based detection and lack of deep behavioral analysis.
API-first Integrated Cloud Email Security (ICES) solutions, exemplified by Abnormal Security, integrate directly via APIs into cloud platforms (e.g., Microsoft 365), offering superior BEC detection through behavioral AI and frictionless deployment without MX record changes.
Microsoft Defender for Office 365 provides unmatched integration within the Microsoft security ecosystem, correlating email threats with signals from Defender for Endpoint and Identity, offering cost efficiency for E5 license holders and reducing mail flow complexity.

Tired of sophisticated phishing attacks bypassing your email security? This guide explores why traditional gateways like Proofpoint may be struggling and evaluates modern alternatives like Mimecast, Abnormal Security, and Microsoft Defender for Office 365.

Diagnosing the Discontent: Why Proofpoint Might Not Be Cutting It

If you’re reading this, chances are you’re an IT professional feeling the strain of an email security gateway (SEG) that isn’t keeping pace with the modern threat landscape. While Proofpoint has been a dominant force in email security for years, its traditional gateway architecture can show its age against today’s sophisticated, socially-engineered attacks. The symptoms are often consistent across organizations.

Common Symptoms of a Faltering Email Gateway

Persistent Phishing and BEC: The most critical symptom. You’re seeing an increase in Business Email Compromise (BEC), credential harvesting links, and sophisticated spear-phishing emails landing in user inboxes. These attacks often lack traditional indicators like malicious attachments or known bad URLs, making them difficult for signature-based systems to detect.
Administrative Overhead: The management console feels clunky and unintuitive. Simple tasks like tracing an email, releasing it from quarantine, or tuning a policy require navigating a complex series of menus. This translates to significant time spent by your security and helpdesk teams.
High False Positive Rate: Legitimate emails, especially from new vendors or partners, are frequently quarantined. This disrupts business operations and leads to “quarantine fatigue” for both users and administrators, eroding trust in the security system.
Poor Cloud-Native Integration: Your organization lives in Microsoft 365 or Google Workspace, but your email security feels bolted on rather than integrated. It lacks deep visibility into internal east-west traffic or emerging threats within collaboration tools like Teams or Slack.

Evaluating the Alternatives: Three Paths Forward

Moving away from an incumbent solution is a significant decision. The right choice depends on your organization’s specific needs, existing technology stack, and risk appetite. We’ll explore three distinct strategic alternatives to augment or replace Proofpoint.

Solution 1: The Incumbent Challenger – Mimecast

Mimecast is often seen as the most direct, like-for-like competitor to Proofpoint. It’s a mature, feature-rich SEG that offers a comprehensive suite of tools, including security, archiving, and business continuity. This is the path for organizations that are comfortable with the SEG model but want a different implementation and feature set.

Key Strengths:

All-in-One Platform: Combines security (Targeted Threat Protection), 100% uptime SLA for email continuity, and a robust cloud archive in a single console.
Mature Feature Set: Includes sandboxing for attachments (Safe Files), URL rewriting (Safe Links), and impersonation protection.
Strong API for Automation: Mimecast provides a well-documented API that allows for automation of common tasks, which is a key consideration for DevOps-focused teams.

Example: Automating Threat Intel with the Mimecast API

A common DevOps task is to programmatically retrieve data. For example, you could use PowerShell to pull a list of users who have clicked a malicious link to trigger an automated response workflow.

# Note: This is a conceptual script. You need to handle authentication with App ID, App Key, etc.

$mimecastApiUrl = "https://us-api.mimecast.com/api/ttp/get-url-clicks"
$requestBody = @{
    data = @(
        @{
            # Filter for clicks within the last 24 hours
            start = (Get-Date).AddDays(-1).ToString("yyyy-MM-ddTHH:mm:ssZ")
            end = (Get-Date).ToString("yyyy-MM-ddTHH:mm:ssZ")
            scanResult = "malicious"
        }
    )
} | ConvertTo-Json

# Assume $headers contains your authorization tokens
$response = Invoke-RestMethod -Uri $mimecastApiUrl -Method Post -Headers $headers -Body $requestBody -ContentType "application/json"

foreach ($click in $response.data.clickLogs) {
    Write-Output "User $($click.userEmail) clicked malicious URL $($click.url) at $($click.date)"
    # Trigger downstream actions: e.g., create a helpdesk ticket, add user to a high-risk group.
}

Solution 2: The API-First, Behavioral AI Approach – Abnormal Security

This represents a fundamental architectural shift. Instead of re-routing your mail flow via MX records, platforms like Abnormal Security integrate directly into Microsoft 365 or Google Workspace via APIs. This approach, often called an Integrated Cloud Email Security (ICES) solution, focuses on behavior rather than signatures.

Key Strengths:

Superior BEC Detection: By analyzing a vast number of signals (communication patterns, identity, content), it excels at catching sophisticated, payload-less attacks that SEGs often miss.
Frictionless Deployment: Setup takes minutes. You grant API permissions, and it starts learning your environment. There are no MX record changes, eliminating the risk of mail flow disruption during migration.

–

Augments, Not Just Replaces: It can be deployed in front of or behind a SEG like Proofpoint or Microsoft Defender, providing an additional layer of defense specifically for advanced threats.

Example: Granting API Access in Microsoft 365

The entire setup revolves around a secure enterprise application consent process. The process is wizard-driven, but understanding the underlying permissions is key.

Navigate to the Abnormal Security portal and initiate the Microsoft 365 integration.
You will be redirected to the Microsoft 365 admin consent screen.
Review the requested permissions. These typically include:
- Mail.Read: To read email content and headers for analysis.
- User.Read.All: To build a baseline of user roles and communication graphs.
- Journaling (via a connector): To receive a copy of all messages for analysis.
Grant consent as a Global Administrator. Once consented, Abnormal begins ingesting data and building its behavioral models.

This API-driven approach means it can also see and remediate internal, east-west threats—an area where traditional SEGs are completely blind.

Solution 3: The Native Cloud Platform – Microsoft Defender for Office 365

For organizations deeply embedded in the Microsoft ecosystem, especially those with E5 licensing, fully leveraging the native security tools is a compelling and cost-effective strategy. Microsoft has invested heavily in Defender for Office 365 (formerly ATP), and its capabilities are now competitive with third-party solutions.

Key Strengths:

Unmatched Integration: Defender shares signals across the entire Microsoft security stack (Defender for Endpoint, Defender for Identity, Microsoft Sentinel). An email-based threat can be correlated with endpoint activity seamlessly.
No Additional Mail Flow Hops: Mail is processed internally within the Microsoft cloud, reducing latency and complexity.
Cost Efficiency: For organizations already paying for E5 licenses, the advanced features are included, eliminating the budget line for a separate email security vendor.

Example: Configuring Anti-Phishing Policies via PowerShell

While the UI is robust, DevOps and security teams can achieve repeatable, auditable configurations using the Exchange Online PowerShell module. Here is how you can create a strict anti-phishing policy targeting key executives.

# Ensure you have the ExchangeOnlineManagement module and are connected
# Connect-ExchangeOnline

# Create a new policy with strong anti-impersonation settings
New-AntiPhishPolicy -Name "Executive Protection Policy" -EnableOrganizationImpersonationProtection $true -EnableTargetedUserProtection $true -TargetedUsersToProtect "ceo@yourcompany.com", "cfo@yourcompany.com" -EnableMailboxIntelligence $true -MailboxIntelligenceProtectionAction "MoveToJunk"

# Apply this policy to the specified executives
New-AntiPhishRule -Name "Executive Protection Rule" -AntiPhishPolicy "Executive Protection Policy" -RecipientIsMemberOf "Executive Leadership" # Assuming you have a group named this

This level of programmatic control allows you to manage security policies as code, which is a massive win for automation and compliance.

Head-to-Head: Feature Comparison

Choosing the right path requires a clear view of how these solutions stack up. This table provides a high-level comparison of the key architectural and operational differences.


Feature	Proofpoint (Baseline)	Mimecast	Abnormal Security	Microsoft Defender
Deployment Model	Secure Email Gateway (SEG) via MX Record	Secure Email Gateway (SEG) via MX Record	API Integration (ICES)	Native Platform (Internal)
Primary Detection	Signatures, Reputation, Rules, Sandboxing	Signatures, Reputation, Sandboxing, Impersonation Checks	Behavioral AI, Identity Modeling, Relationship Graphs	Signatures, Detonation, Campaign Views, ML Models
BEC Protection	Rule-based, relies on keywords and display name spoofing	Good, with specific Impersonation Protection policies	Excellent, core strength of the platform	Good, uses Mailbox Intelligence and Impersonation settings
Setup Complexity	High (MX changes, policy migration)	High (MX changes, policy migration)	Very Low (API consent, journaling rule)	Low (Enable and configure policies)
Ecosystem Integration	Limited (SIEM, SOAR via APIs)	Good (SIEM, SOAR, some endpoint)	Excellent (Deep integration with M365/Google, CrowdStrike)	Unmatched (Native to Microsoft 365, Sentinel, XDR)

Making the Call: Which Solution Fits Your Stack?

There is no single “best” email security platform; there is only the best fit for your organization. Your decision should be guided by your primary pain points and strategic goals.

If your priority is a feature-for-feature replacement with a comprehensive suite including archiving and continuity, and you’re comfortable with the SEG model, Mimecast is a powerful and logical contender.
If your biggest challenge is the 1% of sophisticated attacks like BEC and vendor fraud that bypass everything else, and you want a low-friction, high-impact security layer, an API-first solution like Abnormal Security is the modern choice.
If your organization is standardizing on the Microsoft security stack and wants to maximize value, reduce vendor sprawl, and leverage deep XDR integration, a finely-tuned Microsoft Defender for Office 365 is an extremely capable and efficient solution.

The best course of action is to run a proof-of-concept (POC). Many modern solutions, especially API-based ones, can run in a passive, monitor-only mode, allowing you to see exactly what your current provider is missing without any impact on your production mail flow. Use that data to make an informed decision and finally get ahead of the threats targeting your users.

👉 Read the original article on TechResolve.blog

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Dnyaneshwar Shekade