Definition:

An Opt-in email refers to an email that is precisely demanded by the recipient.

Information:

What an opt-in email means has been a hot topic since the beginning.

“Single opt-in” vs. “Double opt-in”

The phrase single opt-in refers to the efforts taken for signing up for an email. The term double opt-in refers to the event when the subscriber steadily confirms their consent by acknowledging an automated message received at their email address. Advocates of double opt-in may not utilize the term, as they might think that every email identified as “opt-in” must be tested.