The Preheader references the area before the main content. It's an excellent opportunity to grab a bit of extra pre-content web real estate. It's got a degree of prominence in the inbox, so it would be a waste not to use it for promotional purposes. Try popping a couple of links in here. Some companies find that they get the most clicks on links within their preheader
Personas provide a multi-dimensional method of targeting. They’re based, as the name suggests, on a projected persona for each customer ‘type’. Get it right, and personas can help you enormously in both predicting behaviour and personalising your communications. Personas are a powerful technique, and they’re increasingly used to improve the usability and customer centricity of communications.
Alternatively, at least, an eye-catching design. It’s worth letting a proper designer have a go at prettifying your emails. Customers are often opening emails on the go, so you need to work hard to grab their attention. Making your emails nice to look at is a brilliant way to hold their eye. Netflix put time and effort into making their emails stand out, personally and visually – and it pays off for them!