I have reviewed this document as part of the security directorate's ongoing effort to review all IETF documents being processed by the IESG. These comments were written primarily for the benefit of the security area directors. Document editors and WG chairs should treat these comments just like any other last call comments. This document defines a new test command for the Sieve email filtering language that allows for the detection of duplicate emails, as identified by message ID, or more complex string matching in the headers or other parts of the message. The document is easy to understand and covers the primary potential issue of resource exhaustion that might arise from a flood of messages with unique IDs. I consider this document to be READY for publication. -Shaun