I am the assigned Gen-ART reviewer for this draft. For background on Gen-ART, please see the FAQ at < http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>. Please resolve these comments along with any other Last Call comments you may receive. Document: draft-klensin-smtp-521code-05.txt SMTP 521 and 556 Reply Codes Reviewer: Joel M. Halpern Review Date: 12-March-2015 IETF LC End Date: 2-April-2015 IESG Telechat date: 9-April-2015 Summary: This document is ready for publication as a Proposed Standard. Major issues: Minor issues: The description of the 556 reply code in section 4 seems to switch between refering to the generating entity as a client and as a sesrver. I presume this is because the actual sitaution is an SMTP server is trying to pass information onwards, and in that onwards direction it is a client which. But it is still confusing for an SMTP client to make a determination and then an SMTP server which is apparently the same entity to generate the rror code to some other SMPT client. Nits/editorial comments: