4.2 I don't need a full mailing list manager like majordomo, so what's the best way to create a simple newsletter system without it?

Use includes to do something like this:

" In /etc/aliases: mylist: :include:/path/to/test/file and then in /path/to/test/file put one e-mail address to a line. Type newaliases and send a note to mylist@localhost to test it. "