Microsoft 365 Security Backlog 2026

Most Microsoft 365 security backlogs do not fail because the tasks are unknown. They fail because everything gets flattened into one noisy list and the order stops making sense.

That is why I like backlog planning in layers. Fix the paths that hand out access first. Then deal with device trust, mail abuse, data exposure and evidence.

Here is the order that usually gives the best return for a smaller UK tenant.

Priority 1: Identity

1. Enforce MFA properly across privileged and high-risk accounts.
2. Block legacy authentication.
3. Reduce privileged role sprawl.
4. Review break-glass accounts and how they are monitored.
5. Review app consent, enterprise apps and old service principals.
6. Pilot phishing-resistant sign-in for high-risk users where practical.

Reason: if identity is weak, the rest of the stack gets bypassed too easily.

Priority 2: Endpoint

1. Enrol devices in Intune.
2. Onboard Defender for Endpoint.
3. Remove unnecessary local admin.
4. Use compliance to gate access.
5. Tackle unsupported operating systems and stale software.
6. Build patch and coverage evidence you can actually show someone.

Reason: a tenant full of exceptions on unmanaged devices does not stay tidy for long.

Priority 3: Mail

1. Apply or review Defender for Office 365 presets where licensed.
2. Confirm Safe Links, Safe Attachments and anti-phishing coverage.
3. Protect finance and leadership from impersonation.
4. Block or tightly control automatic external forwarding.
5. Review user submissions weekly.
6. Audit inbox rules after compromise.

Reason: mail remains one of the easiest places for abuse, quiet exfiltration and user deception.

Priority 4: Data

1. Review SharePoint external sharing.
2. Remove stale guests.
3. Label obvious sensitive data.
4. Start DLP in monitor mode.
5. Prepare data posture before Copilot expansion.
6. Control high-risk sites with container labels.

Reason: overshared collaboration data keeps turning up in reviews because it is easy to create and easy to forget.

Priority 5: Evidence

Evidence pack	Why
Identity controls	Shows who can access the tenant
Endpoint reports	Shows device coverage and patch state
Mail security config	Shows phishing controls
Sharing review	Shows data exposure control
Incident runbook	Shows response readiness

Evidence sits last in the list, but not because it is optional. It is last because it should be created alongside the work, not instead of it.

A simple way to keep this backlog honest

For each item, keep four fields:

Field	Example
Owner	IT manager
Deadline	30 June
Proof	Screenshot, export, policy name
Exception	VIP device exempt until replacement

That tiny structure stops the backlog becoming a graveyard of good intentions.

What improves trust fastest is clarity. Clear scope, clear owners, clear evidence, and fewer half-finished controls make the whole Microsoft 365 estate feel more deliberate.

References

• Microsoft Entra what's new
• Microsoft Intune what's new
• Microsoft Secure Score
• Microsoft Purview Data Security Posture Management
• Configuring and controlling external email forwarding in Microsoft 365