Fix Microsoft Defender Attack Simulation Emails Not Delivered to Gmail
Question details
Users need to resolve an issue where Microsoft Defender Attack Simulation Training emails fail to reach intended Gmail inboxes, despite sender allowlisting being applied.
- Product
- Microsoft Defender / Gmail
- Device & OS
- not provided
- Scenario
- Administrators are running a simulated phishing or attack campaign targeting users with Gmail accounts.
- Observed behavior
- Attack Simulation messages are reported as started or received in Microsoft Defender, but never appear in the recipient's Gmail inbox.
Ensure you have administrative access to both the Microsoft Defender portal and the Google Workspace Admin console to verify mail flow settings, tracing tools, and compliance logs.
Verify Campaign Settings and Recipient Folders
Check the basic simulation configurations and ensure the email has not been automatically routed to Spam or Trash.
Often, simulation emails are successfully delivered but are filtered out by the recipient's local mailbox rules or default spam filters. Verifying the campaign timeline and checking local folders is the quickest way to rule out basic user-end issues.
Ask the target recipient to thoroughly check their Gmail Spam, Trash, and quarantine folders for the simulation email.
In the Microsoft Defender portal, confirm that the simulation campaign is currently active, scheduled correctly, and has not been paused or limited by its timeframe.
Ensure the tenant, recipients, and simulation permissions meet Microsoft's Attack Simulation Training requirements and are fully provisioned.
Analyze Message Trace and Workspace Logs
Use tracing tools in both Microsoft Defender and Google Workspace to find exactly where the message was dropped.
Contact Microsoft Support for Unresolved Discrepancies
Escalate the issue to Microsoft Support if delivery is reported successfully but Google shows no trace of the message.
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Frequently Asked Questions
Why are my Attack Simulation emails going straight to Gmail spam despite sender allowlisting?
Sender allowlisting alone may not cover the campaign's envelope sender or delivery infrastructure. Gmail's filters might still flag the emails as spam if the underlying infrastructure IPs or envelope addresses aren't explicitly trusted in your Google Workspace settings.
How can I check if Google Workspace is blocking the simulation emails?
You need to log into the Google Workspace Admin console and check the mail-flow, compliance, and quarantine logs for the specific recipient. This will show you exactly why Google rejected or quarantined the incoming message.
What should I do if Microsoft reports the simulation as delivered but it's not in Gmail?
If there is a discrepancy where Microsoft's message trace reports successful delivery but Google has no trace of the message arriving, you should gather your campaign ID, recipient details, timestamps, and tenant information, and contact Microsoft Support for a backend investigation.
