Consider sharing the focus of the email between the call to action you want from your user and offering them something like a discount, early access to a new product, or a free trial period for subscription-based services. Get creative here. Give serious thought to what your customers will find valuable. No one knows their needs better than you and don’t be scared to do some research into what they’d want.
Once your list is targeted, you need to spend an equally large portion of time coming up with a great deal – even if it means you might lose a bit of money on it. The underlying goal of any marketing campaign is to gain new customers, and it’s worth it to significantly reduce your profit margins to gain said customers. Once you have a surgically-honed list and an amazing offer, then you can spend some time on the design, copy, delivery methods, postage rates, date of delivery, size of the mailer…there are a lot of other options to consider, but following the 40/40/20 rule you can see how important audience and offer truly are.