Email marketing is the lifeblood of a lot of small businesses, which makes sense too, as it's continually ranked by marketers as the single most effective tactic for awareness, acquisition, conversion, and retention. But while it can be a driving force behind your business, it's only as strong as your email list.

Simply put, if you're annoying your list of contacts, your email won't be as effective. Without a satisfied email list to send to, you don't have a successful email marketing.

As I've said before, email marketing is (and will continue to be) the most important channel any business can use to continually get their name in front of their past and present clients. The long-term return is that your past clients will remember your name, bring you repeat business and recommend you to friends. Those are positive signals your recipients are sending you.

But what about the negative signals? What are the warning signs your email list will send you when they're not content with your communication strategy? What if they're already giving you this feedback and you just don't realize it?