There's no doubt about it; email marketing has the highest ROI of all other avenues. And whether you're selling online, running a blog, or gathering sales leads, every company needs a healthy email list. But getting the list isn't the problem – the real question is, how do you keep the list engaged? Simple, by following a set of best practices. The email industry is constantly changing. To keep you on top of these changes, we've compiled 10 of the best practices for effective email marketing.