Definition
Sending commercial or informational emails to a list of subscribers. Includes newsletters, promotions, lead nurture sequences, and transactional messages.
Why it matters
Email is one of the few marketing channels an owner actually owns: the list is yours, not rented from a platform that can change its rules or bury your reach overnight. That makes it reliable for turning one-time buyers into repeat customers and for reaching people who already know you. The risk is wearing out your welcome, since sending too often or sending irrelevant offers trains people to ignore or unsubscribe, and a burned list is hard to rebuild.