In Email Marketing, opt-in refers to the process by which a user gives explicit permission to receive email communications from a business or organization. This method ensures that the user is genuinely interested in the content, resulting in higher engagement rates. Opt-in mechanisms can be single or double:
Single Opt-In: The user signs up for emails via a form and is immediately added to the email list. Double Opt-In: After signing up, the user receives a confirmation email and must click a link to verify their subscription.