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 extends the POP3 protocol using the POP3 Extension Mechanism to 1) permit un-encoded UTF-8 in headers 2) add a mechanism to support login names outside ASCII character sets 3) add a mechanism to support UTF-8 protocol-level error strings in a language appropriate for the user The authors have done a good job of identifying the possible security implications of this approach and have also give references to the appropriate documents for the security implications of using UTF-8 in general. I don't see any further issues that need to be addressed here. Catherine Meadows Naval Research Laboratory Code 5543 4555 Overlook Ave., S.W. Washington DC, 20375 phone: 202-767-3490 fax: 202-404-7942 email:  catherine.meadows at nrl.navy.mil