Test your method with something simple and non-controversial to a close friend who can confirm it was a personal message and did not go to the list. There is nothing more embarrassing than sending a personal note to a colleague and later learning it was sent to everybody. The reply function in some mail programs sends the response to everybody imaginable. Listen and absorb for a while to catch the tenor of a new list. Most lists don't encourage personal replies to the whole list, but some do.
Some lists are very busy, some are indolent.
Hopefully someday all lists will have the digest and index features. If you would like to be removed from a discussion list send the message signoff nameoflist or unsubscribe nameoflist to the listserver. If signoff does not work, try unsubscribe . A few other net-etiquette issues Send personal replies or notes to individual subscribers, not to the list. Responses to postings should include some information about the issues to which you are responding.