Electronic Direct Mail is a form of email marketing that you can do with a service like MailChimp or Klaviyo. Basically, the difference between general email marketing and EDM is how personalised it is. With EDM, you’re talking about sending an email or social media ad that is based on the previous actions of a customer - what they’ve bought in the past, what region they live in, what kind of spending habits they have - rather than an announcement to your whole list about a new sale. Find some examples here.