I have always taken it for granted that people know how to send e-mail to a long list of people but not expose the e-mail addresses of people who may wish to keep their addresses private. Well It dawned on me recently that this was not common knowledge when a colleague asked me how to do it.
As ever, rather than write the instructions myself, although they are simple enough, I Googled the problem and came up with a page that describes "how" in far better detail than I could have managed.