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How to Fix Microsoft 365 Emails Quarantined as High Confidence Phish
Question details
Users are experiencing an issue where legitimate outgoing emails are intercepted and quarantined by Microsoft 365 security policies.
- Product
- Microsoft 365
- Device & OS
- not provided
- Scenario
- Sending outgoing emails that contain links to specific, legitimate domains.
- Observed behavior
- The emails are quarantined as High Confidence Phish with a URL Detonation message, even if the linked destination website appears clean in public scanners.
Ensure you have global administrator access to your Microsoft 365 tenant, as resolving this security policy issue requires submitting a formal service request.
Submit a Service Request via Microsoft 365 Admin Center
The most effective way to resolve false positive URL detonations is to have Microsoft Support review the message trace and tenant security logs.
Microsoft 365 threat detection decisions rely on internal reputation data, URL analysis, and specific tenant policies that are not publicly accessible. Public forum moderators lack the security clearance to access these detailed logs.
Therefore, an Office 365 global administrator must escalate the issue directly to Microsoft's technical support engineers for professional diagnostics.
Go to the Microsoft 365 admin center and sign in using your global administrator credentials.
Click on 'Support' or 'Help & support' located at the bottom right of the admin center dashboard.
Follow the on-screen prompts to describe your 'High Confidence Phish' quarantine issue and open a new online service request.
Supply the support engineers with detailed message trace data and the specific URLs triggering the URL detonation.
Boost Your Productivity with WPS Office
While you wait for your Microsoft 365 email quarantine and security policy issues to be resolved, consider using WPS Office for your daily document creation needs. It is a highly compatible, free, and lightweight suite that handles Word, Excel, and PowerPoint files seamlessly without relying on complex cloud tenant policies.
- 1. Download the Installer: Visit the official WPS website and download the free WPS Office installation package.
- 2. Install WPS Office: Run the downloaded file and follow the quick setup wizard to install the software on your device.
- 3. Open Your Documents: Launch WPS Office to easily open, edit, and save your existing Microsoft Office files without formatting issues.
Frequently Asked Questions
What does URL Detonation mean in Microsoft 365?
URL Detonation is a security feature within Microsoft Defender for Office 365. It actively opens links in a secure, virtual environment to check for malicious behavior or payloads before allowing the email to be delivered to the recipient.
Should I remove the flagged link to bypass the quarantine?
It is not recommended to permanently remove the link as a workaround until Microsoft Support investigates the root cause. Removing it prevents the support engineers from diagnosing the false positive and fixing the underlying URL reputation issue.
Why is a legitimate website flagged as a high confidence phish?
Microsoft 365 uses complex internal reputation data, tenant-specific policies, and advanced threat detection algorithms. Even if a website appears clean on public malware scanners, internal security systems may flag it based on historical data, domain patterns, or recent unverified changes.
