Anyone with email has received some sort of marketing via email campaign at some point. This form of marketing gives businesses the opportunity to communicate with existing and potential customers via email.
You want your emails seem as personal as you possibly can. Like it is with many other methods of marketing, treating your customers as individuals can make them more likely to respond positively to your message. For instance, if you are aware of the reasons that they had for signing up for your emails, mention that in your communications with them.