Add email firewall control

Signed-off-by: Bryan Frimin <bryan@frimin.fr>

controls/platform/email-security/PLT.EMAIL.004.email_filtering_and_warning_system.md

@@ -0,0 +1,40 @@
+---
+id: "PLT-EMAIL-004"
+category: "platform/email-security"
+revision-version: 1
+revision-date: "2024-01-07"
+estimate-time: "15m"
+frameworks:
+    - name: "soc2"
+      sections: ["CC6.8", "CC7.2"]
+---
+
+## Purpose
+
+Implement email filtering and warning systems to reduce phishing risks
+and protect employees from malicious emails. This reduces mental load
+on employees and decreases company risk exposure through email-based
+attacks.
+
+## Implementation
+
+### Google Workspace
+
+1. Access [Google Admin Console](https://admin.google.com).
+2. Navigate to Settings
+   ```
+   Apps → Google Workspace → Gmail
+   ```
+3. Configure "Safety" settings:
+   - Attachments Protection
+	 - Scan for anomalous attachment types
+	 - Block attachments with scripts
+	 - Block encrypted attachments from untrusted senders
+   - Links and External Images:
+	 - Enable scanning of linked images
+	 - Identify shortened URLs
+	 - Display warning prompts for untrusted domains
+
+## Evidence
+
+- Screenshot of email security settings in Google Admin Console.