I'm trying to figure out why more of the conversations I find myself involved in are not on the public list. Is it a signal to noise ratio problem?
More likely reflex; posting to the general list leaves your email address exposed on the web for spammers to find and add to their lists. The ~130 spams I receive every day have sharpened my reflexes into almost never sending emails to public aliases.
If we change the publically-available discussion lists to not expose the email addresses of the senders, you'll have fewer people like myself sending to you before sending to the alias. tarl