The Subject line is essential. BCC lets you send a carbon copy to others, but the identity of those others is hidden. This is the BEST way to send something to a bunch of email addresses because it keeps the header short. Lets you set up your own small mailing lists. Attachments let you send files to your friends.
Attachments are also the number one way that viruses are spread across the Net.
You can also set up your own list software with the help of L-Soft. If you have just a few people, though, stick with the mailing list trick from Lesson 7. Other lists can be found at Lizst. You have to set up your program with the correct address, which your ISP will give you. In fact, if you are lucky, your ISP may have a handout that tells you everything you need to know about Usenet.