Security Policy Errors

What to Do When Microsoft Defender Detects a Malicious URL in Email

Natalie Taylor Oct 12, 2026 870 views

Question details

The user received an email containing a link that Microsoft Defender flagged as malicious or phishing, even though the sender's address appears to belong to Microsoft or a trusted source.

How to Handle a Malicious URL Detected by Microsoft Defender in an Email

Product: Microsoft Defender
Device & OS: not provided
Scenario: Reviewing emails in an inbox and encountering a security warning triggered by a URL inside the message.
Observed behavior: Microsoft Defender blocks access or displays a warning that the URL in the email is malicious, despite the sender address looking legitimate.

Before you start

Ensure you have not clicked the flagged link or downloaded any attachments from the suspicious email. If you suspect you have already accidentally clicked a malicious link, disconnect your device from the internet immediately.

Solution 1Recommended

Avoid Interaction and Report the Suspicious Email

The safest and most effective approach is to strictly avoid engaging with the email and escalate it to your IT security team.

Cybercriminals frequently use 'spoofing' techniques to forge sender addresses, making malicious emails appear as though they originate from trusted sources. If Microsoft Defender identifies a threat, you should always trust the security software over the appearance of the sender address.

Do Not Click Links

Refrain from clicking any URLs or downloading any attachments within the email under any circumstances.

Report to Security Team

Forward the email as an attachment or use the 'Report Phishing' button built into your email client to alert your organization's IT or security department.

Delete the Email

Once the email has been successfully reported for verification, delete it from your inbox and clear it from your 'Deleted Items' folder.

Avoid Interaction and Report the Suspicious Email

Security Best Practice: Reporting phishing attempts helps your IT team update security filters, protecting your entire organization from similar attacks in the future.

Solution 2

Verify the Sender Through Alternative Channels

If you believe the email might contain genuinely important information or an urgent request, verify its authenticity without using the provided links.

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Frequently Asked Questions

Why would Microsoft Defender flag an email from a legitimate Microsoft address?

Cybercriminals often spoof the 'From' field to forge the sender's email address. While the address looks legitimate, the actual origin of the email and the hidden URLs inside it are malicious. Microsoft Defender scans the actual URLs and file payloads, triggering the alert regardless of the display name.

What should I do if I accidentally clicked the malicious link in the email?

Immediately disconnect your device from the internet. Run a full system scan using Microsoft Defender or your preferred antivirus software. Additionally, use a different, secure device to change your passwords for any accounts that may have been compromised.

Can I bypass the Microsoft Defender warning if I personally know the sender?

It is highly recommended not to bypass security warnings. Even trusted senders can have their email accounts compromised by hackers who then use them to distribute malware to their contacts. Always verify the link with the sender via a phone call or text message first.

How do I report a phishing email in Outlook?

In Outlook, select the suspicious email, navigate to the Home tab on the ribbon, click the 'Report Message' button, and choose 'Phishing'. This sends the email data to your IT department and Microsoft for analysis, helping to improve spam filters.

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