452 4.3.1 Insufficient system resources

When you use Outlook customers to send and receive messages, you are prompted??

452 4.3.1 Insufficient system resources, the message is still in the Drafts box, and the message has not been submitted to the queue database.

Solution:

Under the Exchange Server installation directory, for example: C:\Program files\microsoft\exchange server\bin, edit the EdgeTransport.exe.config configuration file:

Modify

<add key= "enableresourcemonitoring" value= "true"/>
For
<add key= "enableresourcemonitoring" value= "False"/>

Check the disk free space on the queue database, and modify the path of the queue data file if the space remains 5GB
Edit the EdgeTransport.exe.config configuration file again:
Modify
<add key= "Queuedatabasepath" value = "C:\Program files\microsoft\exchange server\transportroles\data\queue"/>
For
<add key= "Queuedatabasepath" value = "D:\Data\Queue"/>

Restart Exchange's transport service after the operation is complete.

452 4.3.1 Insufficient system resources