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 describes a further extension to the Sieve Vacation extension, allowing multiple auto-replies to the same sender in a single day by adding a ":seconds" parameter. In section 4, it says Security considerations for the Sieve Vacation extension [RFC5230] apply equally here. In addition, implementations SHOULD consider the number of auto-replies that might be generated by allowing small values of ":seconds" (including 0), and MAY impose additional limits on that number. See the Security Considerations section of RFC 3834 [RFC3834] for a fuller discussion. I don't see any other pending issues regarding the security aspect. B. R. Tina http://tinatsou.weebly.com