Outlook Troubleshooting Guide

Outlook Troubleshooting Guide

Outlook Troubleshooting Guide

Experiencing problems with Outlook?

This guide covers the most common Outlook issues, including:
  • Outlook won't open
  • Emails not sending or receiving
  • Inbox not updating
  • Shared mailbox issues
  • Password prompts
  • Sync problems
  • Freezing or crashing
  • Slow performance
Please work through the steps below before logging an IT support request.

1. Completely Close and Reopen Outlook

Many Outlook issues occur because Outlook is still running in the background after being closed.

  • Close Outlook.
  • Press Ctrl + Shift + Esc to open Task Manager.
  • Look for Microsoft Outlook or OUTLOOK.EXE.
  • If it is still running, select it and click End Task.
  • Open Outlook again.

2. Restart Your Computer

A full restart clears temporary issues with Outlook, Microsoft 365 and Windows.

  • Save your work.
  • Restart your PC.
  • Open Outlook again.

3. Check Your Internet Connection

  • Confirm Wi-Fi or network cable is connected.
  • Open a website to verify internet access.
  • If using VPN, disconnect and reconnect if necessary.

4. Make Sure Outlook Isn't Offline

  • Open Outlook.
  • Select Send / Receive.
  • Ensure Work Offline is NOT enabled.

5. Check if Emails Are Being Received Elsewhere

Log into Outlook Web Access.

  • If emails appear online but not in Outlook, the issue is likely Outlook syncing.
  • If emails don't appear online either, the issue may be mail flow or delivery related.

6. Check Junk Email and Focused Inbox

  • Check the Junk Email folder.
  • Check Deleted Items.
  • Check the Other Inbox if Focused Inbox is enabled.

7. Start Outlook in Safe Mode

This disables add-ins and helps identify plugin problems.

  • Press Windows + R
  • Type outlook /safe
  • Press Enter

8. Disable Outlook Add-ins

  • Go to File → Options → Add-ins.
  • Select COM Add-ins.
  • Disable unnecessary add-ins.
  • Restart Outlook.

9. Check Your Password

  • Verify your Microsoft 365 password.
  • Try signing in to Outlook Web.
  • If prompted repeatedly, your credentials may need refreshing.

10. Clear Stored Credentials

  • Open Control Panel.
  • Open Credential Manager.
  • Remove Microsoft Office or Outlook credentials.
  • Restart Outlook.
  • Sign in again.

11. Repair Your Outlook Profile

  • Open Control Panel.
  • Select Mail.
  • Open Email Accounts.
  • Choose Repair.
  • If necessary, create a new Outlook profile.

12. Check Microsoft 365 Updates

  • Install Windows Updates.
  • Update Microsoft Office.
  • Restart your PC.

13. Check if Microsoft Services Are Down

If multiple users are experiencing the same issue, Microsoft services may be unavailable temporarily.

If the issue is resolved

No further action is required.

The majority of Outlook issues are caused by:

  • Outlook processes running in the background
  • Sync issues
  • Microsoft 365 sign-in problems
  • Add-ins
  • Temporary Windows issues
Still experiencing issues?

Please log an IT support request and include:

  • A clear description of the problem.
  • Any error messages.
  • When the issue started.
  • The troubleshooting steps you've already completed.
  • Screenshots, if available.
A white cell phone sitting on top of a wooden table

Outlook Troubleshooting Guide

Still need help?

If this article didn’t solve your issue, our support team is ready to assist you quickly.

© One Group IT — All Rights Reserved