Email marketing is the practice of sending targeted commercial messages to a permission-based list to drive activation, retention, repeat purchase, or referral. Recipients are typically subscribers, customers, or prospects, and the channel is typically managed through an email service provider (ESP) such as Klaviyo, Customer.io, Mailchimp, ActiveCampaign, or HubSpot. It is the highest-ROI direct-response channel for most stages of the funnel because the cost per send is negligible and the list is an owned asset rather than rented attention.
The channel operates on three layers: broadcast (one-to-many newsletters and announcements), lifecycle (automated sequences triggered by customer behavior, like onboarding drips, abandone...