MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
A user reports that they cannot access their Microsoft 365 mailbox via Outlook on the web. Other users can access their mailboxes. What is the most likely cause?
⚠ Common exam trap
Watch out — candidates often confuse authentication issues (password expired) with authorization or licensing issues, assuming that if a user can log in to the Microsoft 365 portal, they automatically have a mailbox.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The user does not have an Exchange Online license assigned
The most likely cause is that the user does not have an Exchange Online license assigned. Without a valid license, the user's mailbox is not provisioned, and Outlook on the Web (OWA) cannot access it. Other users can access their mailboxes because they have licenses, ruling out a service-wide issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The user's password has expired
Why it's wrong here
A password expiry would cause the authentication request to fail at the Microsoft Entra ID layer, blocking sign-in to every Microsoft 365 service—Outlook on the web, Teams, OneDrive, and the admin portal—until the user resets the password. Since the problem is isolated to accessing mail in a web browser, and the user can presumably log into the portal or other applications, expiry is not a valid cause. If the password were actually expired, they would receive a 'your password has expired' prompt and be required to update it before any service is accessible.
- ✗
The Exchange Online service is experiencing an outage
Why it's wrong here
An Exchange Online outage is a service-wide event that typically affects a geographic region or the entire tenant, so multiple users in the same location would be unable to load Outlook on the web simultaneously. You would also see a health advisory in the Microsoft 365 admin center (Service Health) and receive messages with HTTP 500 or similar connectivity errors. Because this is a single-user issue, a tenant-level outage cannot explain the symptom; the problem is more likely related to that user's license or mailbox configuration.
- ✗
The user's browser cache needs to be cleared
Why it's wrong here
Cached browser data or stale JavaScript can occasionally produce a blank OWA page or a redirect loop, but a cache problem would not trigger a license-related error from Exchange Online. Clearing the browser cache is a standard first-line troubleshooting step, yet it is not the root cause here—the user's credential is likely still valid and the browser still loads the login page. If the user lacks an Exchange Online license, no amount of cache clearing will provision a mailbox or grant access to OWA.
- ✓
The user does not have an Exchange Online license assigned
Why this is correct
Exchange Online licenses are assigned per user through the Microsoft 365 admin center or Microsoft Entra ID, and each user needs an active license with the Exchange Online service plan before a mailbox is provisioned. Without that license, the user remains able to authenticate to Microsoft 365 and use other services, but Outlook on the web will fail with a 'no mailbox' or 'license' error because Exchange does not find a recipient object. This exactly matches the reported scenario: one user cannot access their Exchange Online mailbox while other functionality may still work.
Go deeper
Related to this question
Learn chapter
Teams Channels and External Access Governance
Key term
Mailbox
A mailbox is a storage location on a mail server where incoming and outgoing email messages are kept for a user or group.
Key term
Outlook
Microsoft Outlook is an email, calendar, and contact management application that is part of the Microsoft 365 suite, used by businesses and individuals to organize communications and schedules.
About these practice questions
Courseiva writes every MS-102 question from scratch — 712 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more way this is tested on MS-102
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A user reports that they cannot access their Microsoft 365 mailbox from the Outlook desktop client, but they can access it via Outlook on the web. Other users in the same tenant are not experiencing issues. What is the most likely cause?
easy- A.There is a service incident affecting only the Outlook desktop client.
- ✓ B.The user's Outlook profile is corrupted or needs to be re-created.
- C.The user's account has been disabled.
- D.The user's Microsoft 365 license has expired.
Why B: If a user can access their mailbox via Outlook on the web but not the desktop client, while other users are unaffected, the issue is isolated to the local Outlook profile or client configuration. A corrupted Outlook profile is the most common cause and is resolved by creating a new profile. This scenario rules out tenant-wide service incidents, account disablement, or license expiry because those would also block OWA access.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This MS-102 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the MS-102 exam.