Overall, it’s much more effective to include your sales pitch either within or associated with any free advice or information. It’s the soft-sell approach that most customers find much less offensive. But since the whole point of having a private mailing list is to enjoy the benefit of sending messages to an eager and receptive audience (and do it whenever you want), there will also be numerous occasions when you’re simply promoting something. Without including any free information or advice. And therein lies the gold