KB Article – Outlook 2016 Attachments Not Opening with Double-Click

Outlook 2016 Attachments Not Opening with Double-Click

Document ID: KB-OUT-016-ATT
Version: 1.0
Date: 27/08/2025
Author: Ante Crvelin
Audience: IT Infrastructure, Service Desk, End Users
Scope: Applies to Microsoft Outlook 2016 clients (Makita AU).

1. Overview & Purpose

Users may be unable to open attachments in Outlook 2016 when they double-click them. Instead, the attachment only opens when you right-click and select "Open".

This KB provides the resolution, which involves adjusting the mouse double-click speed.

2. Symptoms

Double-clicking an attachment in Outlook 2016 has no effect.
Right-click → Open works as expected.

3. Cause

This issue occurs when the double-click speed setting in Windows is set too fast. The system may not recognise the double-click action correctly.

4. Procedure

Step 1 – Adjust Mouse Double-Click Speed

Open the Control Panel and click Mouse.
- If Mouse is not visible, search for “mouse” in the Control Panel search box and click Change mouse settings.
On the Buttons tab, locate the Double-click speed slider.
Slide the bar to the left (slower).
Click OK to save changes.

👉 Tip: Sliding the bar one step to the left usually resolves the issue. If the problem persists, adjust further.

5. Validation / Testing

Open Outlook 2016.
Double-click an attachment.
Confirm the attachment opens normally without requiring a right-click.

6. Troubleshooting

If the issue continues:

Test double-click behaviour in Windows Explorer (try opening a folder).
Ensure the mouse driver is up to date.
Swap the mouse with another to rule out a hardware issue.

7. Risks / Considerations

This setting applies system-wide, not just in Outlook. Slowing the double-click too much may cause unintended “double-clicks.”
Users should adjust gradually for optimal performance.

8. Related Articles / References

KB-OUT-016-LIC: Office 2016 Activation Error (Unlicensed Product)
Microsoft Docs: Mouse Properties in Windows