Send & Receive Issues

How to Troubleshoot Delayed External Email Messages in Microsoft 365

Partner Editor Sep 28, 2026 869 views

Question details

Users are experiencing 10 to 20-minute delays when receiving email messages from external senders, whereas internal emails are delivered instantly.

How to Troubleshoot Delayed External Email Messages in Microsoft 365

Product: Microsoft 365 / Exchange Online
Device & OS: not provided
Scenario: Receiving emails from senders outside the organization.
Observed behavior: External email messages arrive 10 to 20 minutes late, but internal emails between colleagues are delivered without any delay.

Before you start

Verify your internet connection and check if this delay affects multiple users in your organization or just a single mailbox. Note that deep diagnostic troubleshooting for server-side email routing requires Microsoft 365 administrator privileges.

Solution 1

Report the Delay to Your IT Helpdesk (For End Users)

If you are a standard user experiencing inbound email delays, the issue typically resides at the server or routing level and must be investigated by your IT department.

External email delays are rarely caused by the desktop email client itself. They usually stem from server-level spam filtering, gateway processing, or backend Microsoft 365 routing issues.

Note the email details

Write down the sender's email address, the exact time they claimed to have sent the message, and the exact time it arrived in your inbox.

Contact your administrator

Reach out to your organization's Microsoft 365 administrator or IT helpdesk and provide them with the collected email delivery details.

Request a backend check

Ask the administrator to open a service request with the backend support team if they cannot isolate the issue locally.

Solution 2Recommended

Run a Detailed Message Trace (For Administrators)

Global or Exchange administrators should use the Exchange admin center to track the precise path of delayed messages and identify where the bottleneck occurs.

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Frequently Asked Questions

Why are external emails delayed while internal emails arrive immediately?

Internal emails are routed directly within your organization's Exchange server environment, making delivery nearly instantaneous. External emails must pass through internet gateways, external DNS routing, and inbound spam/malware filters, which can introduce delays if there are connectivity bottlenecks or heavy filtering loads.

Can standard users run a message trace in Microsoft 365?

No, standard end users do not have the required permissions to run a message trace. You must be assigned the Exchange administrator or global administrator role to access the Message Trace tool in the Exchange admin center.

What specific details should I look for in the message trace report?

Review the 'Delivery status' and 'Message events' tabs. Pay close attention to the timestamps between different processing events. A significant gap between the 'Receive' event and the 'Deliver' event usually indicates where the message was held up, such as in a spam filter or a transport rule evaluation.

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