Fix Emails Disappearing Between Proofpoint and Exchange Online
Question details
The user needs to locate emails that were successfully processed by Proofpoint but failed to reach Microsoft Exchange Online inboxes.
- Product
- Microsoft Exchange Online
- Device & OS
- not provided
- Scenario
- Tracking intermittent mail-flow routing failures between a third-party security provider (Proofpoint) and Microsoft 365.
- Observed behavior
- Messages are marked as accepted and delivered by Proofpoint, but completely disappear before reaching the recipient's Exchange Online inbox.
Ensure you have Global Administrator privileges in your Microsoft 365 tenant and access to the Proofpoint administration console before investigating mail flow logs.
Trace Messages and Verify Routing Connectors
Use this method to identify exactly where the email routing failed between Proofpoint and Microsoft 365.
Intermittent routing failures often occur if the inbound connector between Proofpoint and Exchange Online is misconfigured, or if Microsoft 365 is experiencing temporary backend sync issues.
Log in to the Proofpoint administration console. Open the message logs to confirm the missing message was accepted and handed off successfully, and copy its specific Message ID.
Log into the Microsoft Exchange Admin Center. Navigate to Mail flow > Message trace, and run a trace using the sender, recipient, and the Message ID obtained from Proofpoint.
In the Exchange Admin Center, go to Mail flow > Connectors. Ensure your inbound connector from Proofpoint is correctly configured to accept mail to your Microsoft 365 tenant without routing errors.
Submit a Service Request to Microsoft Support
If your connector configuration is correct but intermittent routing failures persist, escalate the issue to Microsoft backend support.
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Frequently Asked Questions
Why are emails passing through Proofpoint but not reaching Exchange Online?
This typically happens due to misconfigured Exchange inbound connectors, expired TLS/SSL certificates, or temporary backend routing failures within Microsoft 365 that prevent the secure handoff of messages from Proofpoint.
How can I check if Proofpoint successfully delivered the email?
You can access the Proofpoint administration console and review your message logs. If the log shows the message status as 'Delivered' or 'Handed off', it means the email successfully left the Proofpoint gateway and was routed toward Microsoft 365.
What information is needed for a Microsoft 365 support ticket regarding missing emails?
When opening a ticket, you should include specific Message IDs, exact timestamps of the routing failure, the sender and recipient email addresses, your current Exchange connector settings, and the exported Proofpoint mail-flow logs.
