Microsoft Exchange server at times prompts the error ‘452 4.3.1 Insufficient system resources’ message in the control panel.

As a part of our Server Management Services, we help our Customers to fix Exchange server related errors regularly.

Let us today discuss the possible causes and fixes for this error.

What causes Exchange error: 452 4.3.1 Insufficient system resources?

The system resource monitoring feature in Microsoft Exchange detects when vital resources, such as available hard disk space and memory, are under pressure. It then takes action to prevent the service to be unavailable.

The 452 4.3.1 Insufficient system resources is one such error shown in the control panel that prevent the message submission. It however tries to deliver the messages in the queue. Once the resource utilization is back to normal, it resumes message submission.

The possible reasons for this error include:

• Shortage of free disk space on which Exchange Hub Transport is queued.
• Back pressure when important resources are under the pressure.
• The volume used by Exchange drop-down or exceeds the specified free disk space threshold.

How to fix Exchange error: 452 4.3.1 Insufficient system resources?

The 452 4.3.1 Insufficient system resources happen mainly when the server runs out of disk space or free memory. The solution to fix this error would be to:

• Increase the amount of free space on the Microsoft Exchange server drive
• Reduce the amount of memory being used by all processes

As we discussed earlier when the disk space threshold set for the volume used by the Exchange exceeds, it can trigger this error. However, the effects of this error vary depending on the threshold set.

For instance, in the case of a medium threshold with 90%, it will stop receiving emails over SMTP from external senders. However, for the high threshold with 99% the mail flow will be stopped completely.

The XML file, EdgeTransport.exe.config in the location \Exchange Server\Bin\ has many configuration options for transport servers in it.

To get Exchange transport to resume message submissions, we can adjust any of the settings below from the EdgeTransport.exe.config file.

• Disable BackPressure: Although Microsoft does not recommend it, it does provide a way to Disable Back Pressure
• Tweak BackPressure thresholds: Adjust the BackPressure parameters if it does not go with your resource usage or server configurations.
• Move the queue database to another volume: Move the queue database to another volume with ample free space.

Move the queue database to another volume

To move the queue database to another volume with ample free space, follow the steps below:

1. Add the following key in the <AppSettings> section in EdgeTransport.exe.config.
   <add key=“QueueDatabasePath” value=”D:\Queue\QueueDB” />
2.  Save the file and restart the Microsoft Exchange Transport service from the Services console or by using the Restart-Service cmdlet (Restart-Service MSExchangeTransport).

Alternatively, we could fix this issue by bringing the disk usage below the threshold limits. Moving mailboxes, clearing logs from the disk, clearing trash, or deleting non-useful files from the drive can help with this.

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Conclusion

In short, Microsoft Exchange server prompts the error ‘452 4.3.1 Insufficient system resources’ message in the control panel when the usage of critical resources is about to exceed its limits. Today, we saw how our Support Engineers fix this error.