Keep in mind that many people are monitoring 30 or more mailing lists and message boards, and would never have time to open every message that they get. They only look at something that has a subject that tells them that it's definitely related to their surnames or other subjects of interest to them. They never open emails with subjects like "Roll Call" or "Kansas City question". So they will miss your message, and you don't want to miss these people, some of them are the best researchers on the internet.