Microsoft Outlook is an essential email and productivity application, but users may occasionally encounter "Out of Memory” or "System Resources” errors, even on computers with sufficient RAM. These issues can disrupt email management, calendar access, and overall productivity. Fortunately, several troubleshooting methods can help resolve the problem in Windows 11.

First, close unnecessary applications running in the background. Open Task Manager and end processes that consume excessive memory. This frees system resources and may immediately improve Outlook performance.

Another common cause is an oversized mailbox. Large PST or OST files can increase memory usage and slow Outlook. Use Outlook's Mailbox Cleanup feature to archive old emails, remove large attachments, and delete unnecessary messages.

Third, disable unnecessary Outlook add-ins. Some third-party add-ins consume significant resources and may conflict with Outlook. Navigate to File > Options > Add-ins, disable suspicious add-ins, and restart Outlook to check if the issue is resolved.

Keeping Outlook updated is equally important. Install the latest Microsoft Office updates to ensure bug fixes and performance improvements are applied.

You can also increase Windows virtual memory settings. Virtual memory acts as additional RAM and helps applications run more smoothly when physical memory becomes limited.

If the problem persists, repair Outlook data files using the Inbox Repair Tool (ScanPST). Corrupted PST or OST files often trigger memory-related errors. In severe cases, specialized Aryson OST recovery software can repair inaccessible or damaged Outlook data files and restore normal functionality.