Whether it's online sales for big-box chains, pure-play retailers or mom-and-pop stores, email marketing has become one of the most effective marketing tactics to reach targeted audiences and boost return on investment and revenue. In fact, email marketing accounts for 5 percent to 10 percent of all e-commerce transactions today. However, not every email is equally effective. Some require much more than just hitting the inbox. I've pulled together my favorite email marketing tips to help you compile a sophisticated email marketing strategy. These tips will help bring your company's future campaigns to the next level by increasing customer engagement and keeping sales up for good.