Exchange Connection Problems

How to View Exchange Online SMTP Relay Message Logs

Maira Mehtab Sep 28, 2026 868 views

Question details

An organization needs to review delivery logs for network devices and scanners that send email via Exchange Online SMTP relay without usernames or passwords.

Product: Exchange Online
Device & OS: not provided
Scenario: Tracking email delivery statuses and troubleshooting failures for devices utilizing SMTP relay.
Observed behavior: Administrators require a way to monitor message trace data in the admin center and verify local SMTP relay server logs for detailed connection information.

Before you start

Ensure you have the necessary administrative privileges, such as the Exchange Administrator role, in the Microsoft 365 admin center to perform message traces.

Solution 1Recommended

Run a Message Trace in the Exchange Admin Center

The primary and most effective method to track messages routed through Exchange Online is by using the built-in Message Trace tool.

Message Trace in the Exchange admin center allows administrators to follow email messages as they travel through your Exchange Online organization. You can determine if a message was received, rejected, deferred, or delivered.

Access the Exchange Admin Center

Log in to the Microsoft 365 admin center with your administrator credentials and navigate to the Exchange admin center (EAC).

Open the Message Trace Tool

In the left navigation pane, go to 'Mail flow' and select 'Message trace' to start a new query.

Filter by Specific Parameters

Enter specific tracking parameters. For exact results, use the message ID if known. Alternatively, filter by the sender's IP address, recipient email address, and a specific date range.

Review Delivery Logs

Run the trace and review the generated logs to confirm whether the SMTP relay emails from your scanners were successfully delivered or rejected by the server.

Data Retention: Summary message trace data is available for 90 days, but traces older than 10 days require an extended message trace which may take several hours to generate.

Solution 2

Review Logs on the Local SMTP Relay Server

For granular connection details before the message reaches Exchange Online, you should check the logs directly on the local server hosting the SMTP relay.

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Frequently Asked Questions

Why are my scanner emails failing via SMTP relay?

Failures are often caused by incorrect port settings, missing TLS requirements, or the sending IP address not being properly whitelisted in your Exchange admin center's inbound connector settings.

Can I search for relayed messages without knowing the Message ID?

Yes, you can search using the sender email address, recipient address, or by filtering for a specific date range, though using the Message ID yields the most precise results.

Where do I find the Message ID for SMTP relay troubleshooting?

The Message ID can usually be found in the header of a delayed or bounced message notification, or within the local SMTP server's transport logs.

Does Message Trace show emails that were blocked by spam filters?

Yes, if the email reached Exchange Online and was then blocked or quarantined by Exchange Online Protection (EOP), the Message Trace will show the status as Filtered or Failed.

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