Microsoft has released a patch for Windows 2000 that will eliminate a vulnerability that exists because a malicious user could issue a specially formatted, non-RFC compliant SMTP command that will result in a Denial of Service attack. This would be carried out more typically through a custom application where the malformed data would cause the SMTP service to fail. Download now to prevent a possible Denial of Service Attack. For More Information visit Microsoft Technet | not yet available

Download Windows 2000 Security Patch: SMTP Rollup for Windows 2000/Server and Advanced Server

The most interesting thing about this fix is W2K_SP3_X86 that it's from SP3 so the wait is nearly over.