Are you checking your subject lines?
Most people don't give much thought to the subject line, or title, of e-mail they send or discussion group messages they post. Guerrillas do. Guerrillas know that the subject line is the first thing a prospective reader sees, and that the quality of the subject line can make the difference between a message that gets read and one that's passed over. And messages that don't get read might as well not have been sent at all.
Think of your subject line as an advertisement for your message. It should identify what the message is about, and be written in such a way that people want to read the message itself. It helps to use power words like Free, New, Information, Security, Proven, Love, and Guarantee in your subject line; words like this have a long history of exciting reader interest. Keep your subject line short--30 characters or less if possible--because many readers won't be able to see more than that.
Make a habit of checking the subject line of every e-mail message and discussion group message you send just before you send it. Make each one a grabber that invites people to read on.