Email Retention in Microsoft 365 — How to Keep What Matters
Introduction
Email retention ensures messages are kept for the correct amount of time for:
- business
- legal
- compliance
- industry regulations
Monster, PIMCO, the Church, and Martin all used different retention needs.
Retention Policy Basics
Retention can:
- Delete after X years
- Keep and then delete
- Keep forever
- Auto-apply by keyword or location
Example Retention Policies
1. Keep 7 Years, Then Delete
New-RetentionCompliancePolicy -Name "7 Years Email"
New-RetentionComplianceRule -Name "7YearEmailRule" -Policy "7 Years Email" -RetentionDuration 2555 -RetentionAction Delete
2. Keep Forever
GUI:
Compliance → Data Lifecycle → Retention → Forever
3. Auto-Apply to Executives
New-RetentionComplianceRule -Name "ExecRetention" -Policy "ExecForever" -UserGroupFilter "JobTitle -eq 'Executive'"
Best Practices
- Always include shared mailboxes
- Use Labels for sensitive groups
- Never auto-delete without approval
- Align with CIS security
- Document your retention plan
Conclusion
Good retention protects the company — and the user.
It ensures you keep what matters and nothing more.
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