How to Fix Outlook Out of Memory or System Resources Error on Windows

If you use Microsoft Outlook regularly for work or email management, you may occasionally run into the frustrating error: “Out of memory or system resources. Close some windows or programs and try again.”

This error can appear when sending emails, opening attachments, adding accounts, or even launching Outlook. Although it sounds like a memory problem, it usually happens due to corrupted Outlook files, faulty add-ins, damaged profiles, or low system resource allocation.

In this guide, we’ll walk you through five effective fixes for the Outlook “Out of memory or system resources” error on Windows.

1. Close Background Apps and Restart Outlook

Sometimes Outlook simply runs out of available resources because other programs are using too much memory or CPU.

1. Press Ctrl + Shift + Esc to open Task Manager.
2. Look under the Processes tab and check if apps like browsers, Teams, or OneDrive are using a lot of memory.
3. Right-click unnecessary programs and choose End task to free up system resources.
4. Close Outlook completely.
5. Reopen Outlook and check whether the error appears again.

This fix works especially well for users working with multiple tabs, office apps, or large attachments.

2. Disable Problematic Outlook Add-ins

Faulty or outdated add-ins often cause memory and resource errors. Disabling them helps isolate the issue.

1. Open Outlook and click File → Options.
2. Select Add-ins from the left sidebar.
3. At the bottom, next to Manage, choose COM Add-ins and click Go.
4. Uncheck all add-ins to disable them temporarily.
5. Click OK, then restart Outlook.
6. If Outlook works normally, re-enable add-ins one at a time to find the problematic one.

Add-ins from antivirus programs, CRM tools, or calendar integrations are the most common culprits.

3. Increase Outlook’s Memory Limit in the Registry

Older versions of Outlook or large email profiles may hit internal memory limits. Increasing this limit through the registry can fix the error.

1. Press Windows + R, type regedit, and press Enter.
2. Navigate to the following path: HKEY_LOCAL_MACHINE\Software\Microsoft\Windows Messaging Subsystem
3. Right-click on the right pane and select New → DWORD (32-bit) Value.
4. Name it: SharedMemMaxSize
5. Double-click it and set the Value data to 512 or 1024 (hexadecimal).
6. Click OK, close Registry Editor, and restart your PC.

This expands the memory allocation available for Outlook’s MAPI subsystem.

Note: Always back up the registry before making changes.

4. Repair Your Outlook Data File (OST or PST)

A corrupted OST or PST file is one of the most common triggers of resource-related Outlook errors.

Steps to Use the Inbox Repair Tool:

1. Close Outlook completely.
2. Navigate to this folder (varies by Office version): C:\Program Files\Microsoft Office\root\Office16\ Look for SCANPST.EXE.
3. Double-click SCANPST.EXE to open it.
4. Click Browse and select your Outlook data file:
   • PST file for POP accounts
   • OST file for Exchange/IMAP accounts
5. Click Start to scan for errors.
6. If issues are found, click Repair.
7. Reopen Outlook once the repair completes.

Repairing these files clears data corruption that may overload Outlook’s memory usage.

5. Create a New Outlook Profile

If your current profile is damaged or misconfigured, Outlook may repeatedly show resource errors. Creating a fresh profile often resolves persistent problems.

1. Close Outlook.
2. Press Windows + R, type control, and press Enter to open Control Panel.
3. Set View by to Large icons.
4. Click Mail (Microsoft Outlook).
5. Select Show Profiles.
6. Click Add, then enter a name for the new profile.
7. Add your email account again by entering your credentials.
8. Select Always use this profile, choose your new profile from the list, and click OK.
9. Open Outlook and check if the error has been resolved.

A fresh profile eliminates old cache data, outdated settings, and corrupted configurations.

Wrapping Up

The “Out of memory or system resources” error in Microsoft Outlook can disrupt your workflow, but the issue is usually easy to fix once you identify the underlying cause. By closing background apps, disabling problematic add-ins, increasing Outlook’s memory limit, repairing data files, or creating a new profile, you can restore normal performance.

After applying these fixes, Outlook should run smoothly again without popping up resource warnings.