There are times when we need not to understand completely 'how things work' we just need to know the tasks they do. Like email delivery assurance system, it is not that necessary for you to fully understand how it works as long as you are aware that it can help in the online business you have. I'm afraid that still most email marketers fail to see the entire picture of online marketing. Though online promotion requires little time, several considerations should be taken into account in order to optimize this type of marketing strategy. It's not enough to just send a newsletter or a promotion to your clients and prospects. Neither is it enough to just place anything you would want your readers to see whenever they open your email. You have to make sure that your emails are reaching the inbox and that readers are getting what they have opted in.