Exchange Online Protection (EOP)

-

  Exchange Online Protection (EOP) is Microsoft’s cloud-based email filtering service that helps protect your organization against:

  • 📧 Spam

  • 🐟 Phishing

  • 🦠 Malware and viruses

  • 🚫 Unsafe attachments and links

It’s built into Microsoft 365 and Exchange Online, but it can also be used to protect on-premises Exchange servers or third-party email systems.

🛡️ What Does EOP Do?

EOP acts as a security gateway between the internet and your mailboxes. It scans all incoming, outgoing, and internal emails for threats and applies your organization’s policies.

🔁 Flow Diagram: How EOP Works

Here’s a simplified flow diagram showing how Exchange Online Protection processes email:

pgsql
         +--------------------+
         |     Internet       |
         +--------------------+
                  |
                  ▼
         +--------------------+
         |     EOP Frontend   |   ⬅️ Connection filtering
         | (Edge protection)  |
         +--------------------+
                  |
                  ▼
        +-----------------------+
        |  Anti-Spam Filtering  |
        | (SPF, DKIM, DMARC,    |
        |  heuristics, blocklists) |
        +-----------------------+
                  |
                  ▼
        +------------------------+
        | Anti-Malware Filtering |
        | (Virus/malware scan)   |
        +------------------------+
                  |
                  ▼
     +-----------------------------+
     |  Advanced Protection Layer  |
     | (Optional: Safe Links,      |
     |  Safe Attachments via ATP) |
     +-----------------------------+
                  |
                  ▼
        +---------------------+
        |    Policy Checks    |  ⬅️ Transport rules (mail flow rules)
        | (DLP, Encryption,   |
        |  disclaimers, etc.) |
        +---------------------+
                  |
                  ▼
      +-------------------------+
      |   Delivery to Mailbox   |
      | (Exchange Online,       |
      |  On-prem, 3rd party)    |
      +-------------------------+

🧰 Key Features of Exchange Online Protection (EOP):

FeatureDescription
Anti-Spam FilteringBlocks known spam and junk mail using Microsoft’s global intelligence.
Anti-Malware ProtectionScans for viruses and malware in attachments and message content.
Connection FilteringBlocks IPs known to send spam (blocklists and allowlists).
Policy EnforcementAllows admins to set mail flow rules (transport rules) like disclaimers, DLP, encryption.
Safe Links (with Defender)Rewrites URLs in emails and checks them at click time.
Safe Attachments (with Defender)Opens attachments in a sandbox environment to detect hidden threats.
QuarantineSuspicious messages are quarantined and users/admins can review them.
Report Junk or PhishingUsers can report bad emails to Microsoft to improve detection.

🎯 EOP in Different Scenarios:

ScenarioIs EOP Used?Notes
Microsoft 365 Exchange Online✅ Built-inEOP is part of your subscription
On-premises Exchange Server✅ OptionalCan route mail through EOP for filtering
Third-party email service (e.g. Gmail)✅ OptionalCan configure mail flow through EOP

💡 Advanced Tip:

If your organization uses Microsoft Defender for Office 365, you get advanced features on top of EOP:

  • Safe Links

  • Safe Attachments

  • Threat Trackers

  • Attack simulation training

✅ Summary:

ComponentPurpose
EOPProtects against spam, malware, and phishing
Built-in?Yes, with Microsoft 365/Exchange Online
Setup needed?Minimal (preconfigured), but can be customized
Can protect on-prem?Yes
   




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