When Outlook stops working as expected, users are quick to reach out—and often under pressure. Whether it’s slow performance, sync issues, or complete failure to launch, diagnosing Outlook problems requires a methodical approach.

This guide outlines essential steps to troubleshoot Outlook, from basic checks to deeper diagnostic tools, helping you determine whether the root cause lies with the client, the server, or in between.

Basic Checks

Before diving into more advanced steps, start with a few quick validations: