JSI Tip 4772. SMTP status code 4.3.1 when sending a message via Telnet?

When you use Telnet to send a message to port 25 of a Windows 2000 SMTP service, it returns status code 4.3.1, Out of Memory?

This will occur if you altered the SYSTEM account permissions. The SYSTEM account needs Full Control of the Mailroot folder and sub-folders.