MS-102 Deploy and manage a Microsoft 365 tenant Practice Question
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?
⚠ Common exam trap
MS-102 often tests the distinction between client-side and service-side failures — candidates may jump to service incidents or licensing, but the key differentiator is that OWA works, which points to a local client issue.
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's Outlook profile is corrupted or needs to be re-created.
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.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
There is a service incident affecting only the Outlook desktop client.
Why it's wrong here
A tenant-wide service incident affecting only the Outlook desktop client is highly unlikely because Exchange Online incidents typically impact all access methods (Outlook desktop, Outlook on the web, and mobile) for the same mailbox service. If Outlook on the web (OWA) remains accessible while the desktop client fails, the problem is almost certainly local to the user's device or profile, not a Microsoft 365 service issue. Additionally, service incidents are visible in the Microsoft 365 admin center and usually affect multiple users, whereas this is a single-user report.
- ✓
The user's Outlook profile is corrupted or needs to be re-created.
Why this is correct
A corrupted Outlook profile is the most plausible cause when a user cannot access their mailbox from the Outlook desktop client but can still access it via Outlook on the web. The Outlook profile contains local configuration data, cache files (.ost), and authentication tokens; if this data becomes corrupted, the client may fail to start, hang, or repeatedly prompt for credentials. Re-creating the profile forces Outlook to rebuild the local cache and re-fetch the server-side mailbox, which resolves the issue without any impact on the server data.
- ✗
The user's account has been disabled.
Why it's wrong here
If the user's account were disabled in Microsoft Entra ID (formerly Azure AD), the user would be blocked from signing in to all Microsoft 365 services, including Outlook on the web, the Microsoft 365 portal, and other workloads like Teams or SharePoint. Since the issue appears to be limited to the Outlook desktop client (with OWA reportedly functional), a disabled account cannot be the cause. Disabling an account also triggers a broader authentication failure that would result in an 'account disabled' error during sign-in, not just a client-specific connectivity problem.
- ✗
The user's Microsoft 365 license has expired.
Why it's wrong here
An expired Microsoft 365 license would revoke the user's entitlement to use Exchange Online, making the mailbox inaccessible from all clients, including Outlook on the web, not just the desktop application. While license expiration may allow the user to sign in, service-specific access (like mail) is denied or returns a licensing error. Because the user can still access their mailbox through OWA, the license is clearly active and assigned, so an expired license cannot explain the desktop-only failure.
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Emergency Access (Break-Glass) Accounts
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.
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.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Microsoft exam blueprint
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.