Data and Audience
Double opt-in refers to email subscribers who request to be added to a mailing list, but before that happens an email is sent asking the subscriber to confirm they do indeed want to be added to the email database. It can be seen as an unnecessary added step by some, but others view it as a great way to refine an email database down to real customers or prospects who are genuinely interested in hearing from you. It also helps reduce bots or other internet spam from winding up on your mailing list with bogus email addresses. According to iterable.com 50% of leading publications used double opt-in to confirm newsletter subscribers.