The MessageUpdater object contains the information used to create a comment or a guestbook entry. This updater is new in API version 1.3.
MessageUpdater
{
string PosterName;
string PosterUrl;
string PosterEmail;
string Body;
bool IsPrivate;
}The PosterName field is ignored when a message is added by an authenticated Zenfolio user. The user's display name is used as the poster name in this case.
AddMessage