Emphasis in dialogue with an exclamation mark is great if you are writing a novel. When you are creating your email campaign you need to emphasize or express a sense of urgency in another manner. Sure they emphasize your point, but you really need this in words and not in punctuation. Using “Go!” is over kill. Instead, “Go” is enough when marketing.
Your sentences need to be written with words that offer a rhythm and sentences with a structure that have importance and urgency already contained. Follow the link to obtain your discount. You do not need the exclamation because “follow” as an action verb provides enough exclamation combined with discount to entice the reader to follow-through on what you desire. Before you send out your next campaign make sure you have a sentence structure with at least one action verb which really makes the individual follow-through to your site.