MS-203 - Microsoft 365 Messaging Troubleshooting Message Transport Questions and Answers

Question 1

A user reports to the messaging administrator that an important email sent to an external partner was never received.
The partner's IT team insists the message never reached their mail servers.
Which tool should the administrator use FIRST to determine the final delivery status of the message from the Microsoft 365 perspective?

Accepted Answer

Message trace in the Exchange admin center

Answer

Mail flow dashboard in the Exchange admin center

Answer

Microsoft Defender 365 audit log

Answer

Service Health dashboard in the Microsoft 365 admin center

Question 2

A user receives a Non-Delivery Report (NDR) with the enhanced status code '5.7.1'. Which of the following is the most common reason for this type of NDR?

Accepted Answer

The message was rejected due to a permissions issue or a mail flow rule.

Answer

The recipient's mailbox is full.

Answer

The recipient's email address does not exist.

Answer

A temporary network issue occurred on the receiving server.

Question 3

Your organization has configured an outbound connector to route all outgoing mail through a third-party cloud archiving service. Shortly after, you receive reports that external recipients are not receiving your emails, and bounce messages indicate an SPF failure. What is the most likely cause of this issue?

Accepted Answer

The organization's public SPF record in DNS has not been updated to include the third-party service.

Answer

The organization's MX record is pointing to the wrong service.

Answer

The outbound connector in Exchange Online is disabled.

Answer

The third-party service does not support TLS encryption.

Question 4

A mail flow rule with priority 0 is configured to bypass spam filtering for messages from a specific partner domain and has the 'Stop processing more rules' action enabled. A second rule with priority 1 is configured to prepend '[EXTERNAL]' to the subject of all messages received from outside the organization. Why would an email from the partner domain NOT have the '[EXTERNAL]' subject tag?

Accepted Answer

The 'Stop processing more rules' action on the priority 0 rule prevented the priority 1 rule from being evaluated.

Answer

Mail flow rules cannot modify the subject line of a message.

Answer

The priority 1 rule has a syntax error and is being skipped.

Answer

A spam filter action always takes precedence over a subject line modification.

Question 5

Upon inspecting the headers of a failed email, a messaging administrator sees the authentication result 'dkim=fail (body hash did not verify)'. The sender has confirmed their DKIM public key is correct in DNS. What is the most likely cause for this specific failure?

Accepted Answer

The message body was altered in transit after it was signed.

Answer

The DKIM private key used to sign the message is corrupted.

Answer

The CNAME records for DKIM are pointing to the wrong location.

Answer

The recipient's mail server does not support DKIM verification.

Question 6

An administrator needs to investigate reports of intermittent, widespread email delays within the last 24 hours. They need a high-level, aggregated view of mail flow, including the status of connectors and any messages that are queued or deferred. Which tool in the Exchange admin center provides the best starting point for this type of investigation?

Accepted Answer

Mail flow dashboard

Answer

Message Trace

Answer

Non-delivered reports

Answer

Mail flow reports under 'Reports'