Definition - What does Transactional Email mean?
Techopedia explains Transactional Email
Companies that send transactional emails may spend quite a bit of time looking at what works best and what recipients will respond to. Companies have developed sets of "best practices" for writing and creating transactional emails. For instance, transactional email senders respond to the ways that readers read these emails, often skimming or scanning them for information. They may also include particular features like a reply-to address, information about where the message is coming from, and appropriate subject lines to help orient readers.
Another important issue about transactional emails is how much plain text is in an email, as compared to how much functional HTML code is involved. The more functionality the transactional email is meant to facilitate, the more HTML would need to be included. For instance, some transactional emails for reservations would need a lot of specific hyperlinks and even some types of pointers to where recipients can enter information about themselves in contact fields.