Double opt-in is an expression related to the way in which a mailing list is created, i.e. the way in which a person’s data is included as a recipient within a commercial or advertising e-mail distribution list.
Double opt-in is a system for registering user data as a recipient on a mailing list by which the user expressly and unequivocally accepts and confirms his or her consent, although always revocable, to receive communications via his or her e-mail address. The term double opt-in refers to the fact that, normally, the user would have included his data as a subscriber through a form on the Internet and, before starting to receive commercial communications, he would receive an e-mail at his e-mail address requesting confirmation of his authorization to receive such commercial communications. A negative response or lack of response to this initial email would indicate that the user has not confirmed his or her authorization and, therefore, the user cannot be sent commercial communications under penalty of committing a spam crime.
This system greatly reduces the risk of users inadvertently giving away their data by not consulting the terms of use when participating in online games, surveys, voting or making use of free WIFI services, etc. although it is not currently a requirement under Spanish law.
The Internet Advertising Bureau has published a Practical Guide to E-Mail Marketing in which it explains the different ways of registering users on a mailing list, in addition to double opt-in.
