What is double opt-in in email marketing?

• A. A method to double the number of subscribers instantly.
• B. A process for deleting inactive emails.
• C. A confirmation step where a subscriber must confirm their email after signup; improves deliverability and reduces spam complaints.
• D. A feature to automatically verify syntax.

Answer: (C)

Double opt-in is a two-step signup process: after someone signs up, they must confirm their email address by clicking a link in a follow-up message before they’re officially added to the list. This verifies both the address and the subscriber’s intent to receive emails. The result is better deliverability and fewer spam complaints because you’ve obtained explicit consent and confirmed the address is real. It also helps with compliance by showing that the user opted in. The other choices don’t fit because they describe actions like instantly doubling subscribers, deleting inactive emails, or automatically verifying syntax—none of which involve confirming the subscriber’s intent to opt in.