So ask yourself, is yours an expensive course that needs a lot of credibility to convince people to purchase it? Is it a free course you are launching and so may need less information and more hype and emotion? Is it a course series you are trying to encourage a commitment to? Are you one Udemy course among 100 competing courses on the same topic?   Are there obvious challenges or objections that people will have to taking your course, such as a high price or hard to achieve objectives?  Are you in a niche market and therefore need to really work hard to keep anyone remotely interested in your topic in your sales funnel?
Your automated sequence of emails needs to reflect the different stages of the sales funnel process as depicted in the diagram above. Automated emails ideally should guide your prospective students somewhere from the “interest phase”, where they have signed up for a newsletter or downloaded a lead magnet, through to purchase of your course. This requires a good bit of thought to create the right messaging, frequency and content offer.
In marketing automation, Ryan Deiss, co-founder of Digital Marketer, often describes the sales funnel as a multi-step, multi-modality process that moves prospective browsers into buyers. It's multi-stepped because lots must occur between the time that a prospect is aware enough to enter your funnel, to the time when they take action and successfully complete a purchase. 
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