In normal cases, since this is the final stage of open community review, the IESG prefers that comments on Last Calls be sent to the ietf at ietf.org list. Authors, WG Chairs and the responsible Area Director are presumed to see all such messages, but they may be copied if the person sending a comment so desires.
It is appropriate to send purely editorial or typographical comments only to the authors, WG Chairs, and responsible Area Director.
If substantive discussion of a technical comment is needed, it is often appropriate to move that discussion to the WG list, once the comment has been made on the IETF list. (For non-WG drafts, it should normally stay on the IETF list.)
In exceptional cases, a comment may be sent only to iesg at ietf.org. However, the IESG will normally need to discuss these comments with the authors, the WG Chairs, and possibly with the WG as a whole. Once a comment is sent to the IESG, it becomes a contribution to the IETF standards process, even if anonymity is requested.
From a practical point of view, Last Call comments should preserve the beginning of the original subject header, up to at least the end of the draft name. For example, a comment on:
Last Call: draft-ietf-pigeon-post-02.txt (Avian Mail Transfer Protocol) to Proposed Standard
could carry a subject such as
Re: Last Call: draft-ietf-pigeon-post-02.txt - what about avian flu risk?
This is to ensure that Last Call comments can be automatically sorted.
Sometimes, a set of related drafts are the subject of a single last call. Please ensure that it is clear which draft is subject of a comment.
There are some organized review teams in the IETF (e.g. Gen-ART and the Security Directorate). Reviews from such teams should be made available to the community if they are intended as Last Call comments.