Calls to action in emails is not much different than calls to action for landing pages: Give people just enough information to take the action you want them to, and little else. Political campaigns and non-profits (at least from successful organizations) are pros at this. Most of the time it is a short teaser and a prominent call to action button. Back to the similarities, paragraphs with off direction sentences are not seen in landing pages, the trendy style is short content blocks of icons and a sentence, for an email the equivalent are bullet points/numbered steps.

Each email should have a well defined, ideally singular purpose, unless it is something like a newsletter, where the reader is more accepting of less relevant content before reaching the more valued information (and even that is not guaranteed.)