abstract:Opt-in email is a term used when someone is given the option to receive "bulk" email, that is, email that is sent to many people at the same time. Typically, this is some sort of mailing list, newsletter, or advertising.
Practically, what this all means is that for the first time marketers can speak specifically to those users who they know something about and have already built a relationship with, either on Facebook or through a sign-up at a brick and mortar store, or an opt-in email program, or any other online or offline channel.
In an email, Biggar said that requiring an opt-in for her company's service would put real-world stores at a disadvantage as they compete with online retailers that track shoppers' behavior from the moment they enter a website.
Perhaps you acquired a list of subscribers that did not explicitly provide opt-in permission to receive your mail or you are still automatically subscribing email addresses obtained through trade show giveaways or other promotions.