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How can you configure advanced DLP (Data Loss Prevention) rules in Microsoft 365 to prevent data leakage between two internal tenants using custom regex patterns and exclusions?
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To configure advanced DLP rules in M365:
**Create DLP Policy**
• At the source, go to **Microsoft 365 Compliance Center > Data Loss Prevention > Create a policy**.
• Select **Custom policy** and choose locations (Exchange, SharePoint, etc.).
**Define Sensitive Info Type with Regex**
• In the policy, create a **Custom Sensitive Info Type**.
• Use the regex pattern to define what data you want to detect (e.g., AB\d{8} for account numbers).
• Set **Confidence Levels** for accuracy.
**Set Exclusions**
• Under **Except when**, define exclusions like:
o **Recipient domain** (e.g., exclude certain domains within internal tenants).
o **Sender domain** or specific users/groups.
**Configure Actions**
• Choose actions such as **block**, **restrict**, or **notify** based on the policy triggers.
**Test and Deploy**
• Test the policy using **simulation mode** to ensure accuracy.
• Review **DLP reports**, fine-tune if needed, then deploy.
Tuned policy will block or monitor sensitive data transmission between internal tenants, with necessary exclusions applied.
DLP policies will need to be deployed within **both** source tenants.