Security Policy Errors

How to Unblock a Legitimate Domain Flagged as Phishing in Microsoft 365

Steve K Oct 13, 2026 869 views

Question details

The user needs to resolve an issue where their legitimate business or nonprofit domain has been mistakenly classified as a phishing site by Microsoft.

How to Unblock a Legitimate Domain Flagged as Phishing in Microsoft 365

Product: Microsoft 365
Device & OS: not provided
Scenario: Managing domain reputation to restore email delivery and unblock website access.
Observed behavior: Microsoft security systems incorrectly flag a legitimate domain as phishing, resulting in blocked email delivery and a damaged domain reputation.

Before you start

Ensure you have global administrator credentials for your Microsoft 365 tenant, as standard users cannot submit domain delisting requests.

Solution 1Recommended

Submit a Delisting Request via Microsoft 365 Admin Center

Use this method to contact Microsoft support and request a manual review to clear your domain's reputation.

Microsoft's automated security systems can occasionally misidentify legitimate websites as malicious. Submitting a direct service request allows backend engineers to investigate the false positive and clear your domain from the block lists.

Sign in to the Admin Center

Navigate to https://admin.microsoft.com and log in using your Microsoft 365 administrator account.

Access the Support Portal

On the left-hand navigation menu, click on 'Help & support' or 'Support' to open the support panel.

Create a New Service Request

Select 'New service request'. In the description box, clearly explain that your legitimate business or nonprofit domain is being incorrectly blocked as a phishing site.

Submit for Backend Review

Provide your contact information and submit the request. A Microsoft support representative will investigate the backend block lists and process the appropriate delisting request.

Submit a Delisting Request via Microsoft 365 Admin Center

Support Options Missing?: If you do not see the option to create a new service request directly, use the search bar in the support pane to search for 'delist domain', then select the contact option provided at the bottom of the relevant articles.

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Frequently Asked Questions

How long does it take for Microsoft to unblock my domain?

Once a delisting request is submitted through the Admin Center, it typically takes 24 to 72 hours for Microsoft to investigate the false positive and update their backend security block lists.

Can I submit a domain delisting request without an administrator account?

No, creating a service request for domain reputation issues requires administrator privileges. You must contact your organization's IT admin to submit the request on your behalf.

Why did Microsoft mistakenly flag my domain as phishing?

False positives can occur due to sudden spikes in email volume, compromised user accounts sending spam, suspicious keywords in bulk emails, or sharing an IP address with a malicious sender on a shared hosting plan.

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