There are 3 types of emails that most people use for their email programs.
Email newsletters - Easily the most popular type of email campaign, newsletters are regular emails sent to a subscribed list of recipients containing curation informational content (often blog posts, news articles or helpful resources).
Transactional emails - These emails are messages sent to individual recipients as a result of a commercial action or other action they took on your website, store or application (e.g. purchase confirmations or password changes)
Lead nurturing emails - These emails are often a thoughtfully created sequence of emails personalized to each recipient to carry individuals who are new to your sales funnel through to making a purchase.