Outlook for Microsoft 365 is ignoring not junk selection

Question

Incoming email is going to the Spam folder and selecting not junk setting does not change the behavior. Selecting does move the email to inbox. Looking at the Junk Mail Options see the option setting is No Automatic Filtering, The email sent to spam is in the Safe Senders and the receiving email is in the Safe Recipients, there is nothing in the Block Senders and this is not international email.

Answer 1

Hi techcoor,

Thank you so much for the detailed follow-up, and I'm glad to hear the Microsoft 365 Admin Center access issue has been resolved. You are absolutely right, and I really appreciate you working through this so patiently. Based on what you have shared, the affected mailbox is a Gmail account added to Outlook, and the same message from a Gmail sender:- Arrives correctly in the Inbox when received in the Hotmail (Outlook.com) account.

• Is placed in the Spam / Junk folder when received in the Gmail account.

This confirms that the issue is happening on the Google / Gmail side, not on the Microsoft side. When a Gmail account is added to Outlook (via IMAP), Outlook essentially just displays the folders that Gmail's own server-side filters have already sorted the mail into. That means:

• Microsoft 365 tools like the Exchange Admin Center, Microsoft Defender, and tenant anti-spam policies do not apply, because those only manage Exchange Online mailboxes, not Gmail.
• The decision to route the message to Spam is made by Google's spam filter before Outlook ever sees it.

Please accept my apologies for the earlier guidance not lining up with your actual setup, since your original post referenced Outlook, I initially assumed it was a Microsoft 365 tenant mailbox. Thank you for clarifying the setup, it makes the picture much clearer now. To resolve this, the changes need to be made directly in Gmail:

1. Sign in to mail.google.com with the affected Gmail account.
2. Open the Spam folder and locate one of the affected messages.
3. Select the message and click Not spam
4. Go to Settings (gear icon) > See all settings > Filters and Blocked Addresses tab.
5. Click Create a new filter, enter the sender's Gmail address in the From field, and click Create filter.
6. Check Never send it to Spam (and optionally Always mark as important), then click Create filter.

Once these changes are applied, future messages from that sender should land directly in the Gmail Inbox, and by extension, in the corresponding Outlook Inbox folder.

If the issue continues, the most reliable next step is to contact Google Support directly, as they are the only ones with visibility into Gmail's server-side filtering decisions. Thank you again for your patience and cooperation through this. Please let me know if you need anything else.

Answer 2

Hi techcoor,

Good day, and I appreciate the detailed description of your issue. I understand that you are experiencing an unexpected issue in Classic Outlook where emails from a safe sender keep being moved to the Junk Email folder, even though the sender is trusted. As a forum moderator, I genuinely wish I could directly access your account or step into the backend systems to diagnose and resolve this for you. Unfortunately, my role here is limited to providing general guidance and solutions that you can apply from your side.

From my research, in Microsoft 365 cloud mailboxes, messages can still be delivered to the Junk Email folder because of Exchange Online Protection / Microsoft Defender anti-spam policies or Zero-hour Auto Purge (ZAP), even if Outlook's local Junk setting is set to No Automatic Filtering. Microsoft's official documentation confirms that "Microsoft 365 uses a mail flow delivery agent to route messages to the Junk Email folder. It does not use the junk email rule in the mailbox," meaning the client-side junk settings on your mailbox have no effect on how the cloud service delivers spam-classified messages.

For an issue of this nature, I would recommend reaching out to your IT administrator for further investigation. They can perform the following from their side:

1. Run a message trace in the Exchange Admin Center to confirm why the message was delivered to Junk.
2. Use the Get-MailboxJunkEmailConfiguration cmdlet in Exchange Online PowerShell to view the mailbox's local junk email settings for context.
3. Check Microsoft Defender portal > Email & collaboration > Policies & rules > Threat policies > Anti-spam policies to see whether any spam / phishing / bulk actions are being applied.
4. Review the anti-spam message headers on one of the affected messages to identify exactly which verdict (Spam, High-confidence spam, Phishing, Bulk) triggered the move to Junk.

If needed, they can also add the trusted sender to any of the following:

• The Tenant Allow / Block List
• The allowed senders / allowed domains list in the anti-spam policy (Microsoft recommends only using these for temporary testing, as they bypass most email protection).
• A mail flow rule to set the SCL or bypass filtering.
• The connection filter (IP Allow List) in the anti-spam connection filter policy.

In the meantime, you can also try the following from your side:

• Check whether the same behavior happens in Outlook on the web. If it also happens in OWA, the issue is almost certainly server-side filtering rather than a Classic Outlook client issue.
• View one of the affected messages' details: right-click the email > View > View message details to check the message headers for anything unusual (e.g., a high SCL / BCL score).

If the sender is genuinely trusted and messages are still repeatedly misclassified, I would recommend collecting the message trace details for one affected message, along with the Defender Explorer detection reason, and submitting a service request with Microsoft Support. A technical support engineer can review the anti-spam verdict, verify the tenant's anti-spam configuration, and coordinate any adjustments needed. If further attention is required, they can escalate the case to a specialized team for deeper analysis. For detailed instructions on how to get support, please refer to Get support - Microsoft 365 admin. If you don't know who your IT administrator is, please refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support 

For references: 

Trace an email message in Exchange Online | Microsoft Learn

Set-MailboxJunkEmailConfiguration (ExchangePowerShell) | Microsoft Learn

Configure junk email settings on Exchange Online mailboxes - Microsoft Defender for Office 365

Anti-spam protection - Microsoft Defender for Office 365 | Microsoft Learn

Create allowlists - Microsoft Defender for Office 365 | Microsoft Learn

For additional assistance, use this link to find the appropriate contact number from your region: Global Customer Service phone numbers - Microsoft Support 

I hope this information is helpful and provides you with a clear path forward. Please know that even though I cannot directly intervene, pointing you toward the correct, specialized support is the most effective help I can offer from my position. Thank you for your patience and understanding. Please let me know if you need anything else.

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