How to Fix Slow Email Loading in New Outlook

Some users may experience slow email loading or delays when opening emails in New Outlook for Windows.

Here are some simple troubleshooting steps you can try.

1. Test Outlook on the Web

Open Outlook in your web browser and check the same mailbox.

• OWA is fast, New Outlook is slow → The problem is likely with the Outlook app or computer.
• Both are slow → The issue may be related to the mailbox, network, or Microsoft 365 service.

2. Restart New Outlook

Close Outlook completely and open it again.

If Outlook is still running in the background:

1. Open Task Manager.
2. Find Outlook.
3. Select End Task.
4. Open New Outlook again.

3. Repair New Outlook

Go to:

Settings → Apps → Installed Apps → Outlook → Advanced Options

Try Repair first.

If the problem continues, you can consider Reset, but make sure the mailbox is fully synchronized with Microsoft 365 first.

4. Check Shared Mailboxes

If the user has access to many shared mailboxes, this can affect Outlook performance.

Check whether the user still needs access to all shared mailboxes, especially large ones.

5. Check Add-ins

Go to:

New Outlook → Settings → General → Manage add-ins

Disable unnecessary add-ins and test Outlook again.

6. Update Outlook and Windows

Make sure both New Outlook and Windows are up to date. Updates may include performance and bug fixes.

Quick Tip

The easiest way to identify the problem is to compare New Outlook with Outlook on the Web.

If Outlook Web works normally but New Outlook is slow, focus your troubleshooting on the Outlook app and the computer.

If both are slow, investigate the mailbox, shared mailboxes, network, or Microsoft 365 service.