Send & Receive Issues

Fix Microsoft 365 Users Not Receiving One-Time Passcode (OTP) Emails

Maira Mehtab Sep 22, 2026 869 views

Question details

Users are unable to receive automated one-time passcode (OTP) emails from a specific external organization, even though standard emails from other domains arrive normally and the sender has been added to the Safe Senders list.

Product: Microsoft 365
Device & OS: not provided
Scenario: A team needs to log into a third-party portal but is blocked because the required authentication passcode emails are failing to reach their Microsoft 365 inboxes.
Observed behavior: The expected one-time passcode emails do not appear in the inbox or junk folder, despite user-level Safe Senders configurations, while generic emails from domains like Gmail are delivered successfully.

Before you start

Ensure you have Exchange Administrator or Global Administrator privileges in your Microsoft 365 tenant, as investigating tenant-level mail flow and quarantine requires admin access.

Solution 1Recommended

Use Message Trace and Check Microsoft Defender Quarantine

Identifying exactly where the email was blocked or routed within your tenant is the most effective way to resolve delivery failures.

Often, automated emails from third-party organizations are flagged by Microsoft 365 security policies before they ever reach the user's mailbox, making user-level Safe Senders lists ineffective.

Log in to the Exchange Admin Center

Navigate to admin.exchange.microsoft.com and log in with your Microsoft 365 administrator credentials.

Run a Message Trace

Go to Mail flow > Message trace. Enter the sender's email address and the recipient's address, then run the trace to see if the message was rejected, blocked, or delivered elsewhere.

Check Microsoft Defender Quarantine

Open the Microsoft 365 Defender portal. Navigate to Email & Collaboration > Review > Quarantine to see if the OTP emails were intercepted and flagged as spam, phishing, or bulk mail.

Release the Email

If you find the missing passcode emails in quarantine, select them and choose 'Release' to deliver them to the intended recipient's inbox.

Message Trace Delays: Message traces for emails received within the last few hours process almost instantly, but older messages may take several hours to generate a report.

Solution 2

Review Anti-Spam Policies and Sender Authentication

Sometimes external organizations have misconfigured SPF, DKIM, or DMARC records, causing Microsoft 365 to reject their automated emails.

Solution 3

Submit a Microsoft 365 Support Request

If message traces show no record of the email hitting your tenant, the issue might be on the sender's side or require advanced Microsoft support to unblock an IP.

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Frequently Asked Questions

Why are emails from Gmail delivered but not OTP emails from a specific organization?

Organizations sending automated OTPs sometimes have misconfigured email authentication records (SPF, DKIM, DMARC), causing stringent security filters in Microsoft 365 to reject or quarantine them. Major providers like Gmail usually have properly configured authentication, so their emails pass through the filters.

Does adding a sender to the Safe Senders list guarantee delivery?

No. The Safe Senders list in Outlook applies at the user mailbox level. If the email is blocked at the tenant level by Microsoft Defender anti-spam, anti-phishing, or malware policies, it will never reach the user's mailbox to be evaluated against their personal Safe Senders list.

What if the Exchange Message Trace shows no record of the email?

If the message trace in the Exchange Admin Center shows no results for the expected email, the message never reached your Microsoft 365 tenant. The sender's email server likely failed to send it, or it was dropped before reaching Microsoft's network. You will need to contact the sending organization's support team.

Outlook & Email Problems