The answer is that the user does not have an Exchange Online license assigned. Without this license, the user’s mailbox is never provisioned in the service, so Outlook on the Web (OWA) cannot locate or open it, while other users with valid licenses access their mailboxes normally. On the Microsoft 365 Administrator MS-102 exam, this scenario tests your understanding of how licensing directly controls service provisioning—a common trap is to assume a network or authentication issue when the real cause is a missing license assignment. A reliable memory tip is “No license, no mailbox,” reminding you that every user must have an Exchange Online license before their mailbox exists in the cloud.
MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
This MS-102 practice question tests your understanding of deploy and manage a microsoft 365 tenant. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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
Password expiration would prevent sign-in to all Microsoft 365 services, not just Outlook on the web.
✗
The Exchange Online service is experiencing an outage
Why it's wrong here
If there was an outage, other users would also be affected.
✗
The user's browser cache needs to be cleared
Why it's wrong here
While possible, this is less likely than a licensing issue.
✓
The user does not have an Exchange Online license assigned
Why this is correct
Without a license, the user cannot access Exchange Online services.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates 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.
Detailed technical explanation
How to think about this question
In Exchange Online, mailbox provisioning is tied to the Exchange Online license assigned via the Microsoft 365 admin center. When a license is removed or not assigned, the user object still exists in Entra ID, but the mailbox is soft-deleted or never created, causing OWA to return an 'access denied' or 'mailbox not found' error. This is distinct from authentication failures, which occur at the Azure AD level before Exchange Online is reached.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MS-102 question in full detail.
Deploy and manage a Microsoft 365 tenant — This question tests Deploy and manage a Microsoft 365 tenant — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 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.
What should I do if I get this MS-102 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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 via OWA but not Outlook desktop, it often indicates an authentication or client configuration issue rather than a service outage. Disabled MFA would affect both. A service incident would affect many users. License issues would also affect OWA. The most likely cause is that the user's profile is corrupted or authentication token has expired.
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Question Discussion
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