Opt-in is the short form of "opting in." It means that someone wants to be involved in something. In the age of technology and the world of sales, the term means that someone has given you permission to send them emails.
It's not necessary to get an opt-in if you're just sending a single email to a prospect or customer, maybe letting them know that you're offering a door-buster sale on Saturday. But an opt-in is essential if you intend to add them to any kind of emailing list. Opting in usually occurs when someone signs up for a series of emails, such as an e-newsletter or coupons for specific products.
The basic rule is that an email to one or two recipients doesn't require an opt-in, but if you send the email to a large group all at once, you must make sure that all the recipients have agreed to receive such emails from you or your company.
Unconfirmed opt-ins can occur when someone visits and somehow registers with your website when your website is set up in such a way as to collect their information.
You've probably encountered these a time or two yourself. You're searching for information and you click on a website that you think will provide it. Instead of displaying the article or information, your entire monitor fills up with a simple question, something seemingly harmless like, "Do you really want to read this?" If you click yes, you may have just committed yourself to an unconfirmed opt-in. When you begin receiving copious emails from the site, you might not even understand why it's happening.
The CAN-SPAM Act
Not only can an unwelcome mass emails turn off your potential contacts and customers, but some practices are against the law. The federal CAN-SPAM Act was enacted in 2003 to regulate commercial emails. The Act requires that you clearly state somewhere in your emails that the recipient can opt-out at any time and that you tell them how to do so in clear terms.
When someone does opt out, you must make sure your system is set up to remove them from your list within 10 business days. The Act applies to all commercial emails and the penalties can be steep, upward of $40,000 as of 2017, so you might want to review the terms of the legislation.
Some companies use double opt-in systems to be absolutely certain that the recipient wants their emails. The recipient fills out a form on a website or otherwise gives permission for the first opt-in. Then the recipient receives a second, automated email asking them to click on a link to confirm that they want to sign up.
Reputable companies always use opt-in lead lists when they're sending out email marketing campaigns. Sending emails to large numbers of recipients who haven't opted is spamming, and it's highly unprofessional in addition to being against the law.
Even if you're not technically spamming a prospect because you received permission from them in the past, they may forget that they've given you permission. If they think you're a spammer, this may be all it takes to blacken your reputation online. Using double opt-in practices when practical can protect you against this kind of misconception. Prospects are more likely to remember the sign-up process if they have to take that second step.