Regardless of what type of marketing messaging you're doing, you'll need to provide a methodology for the subscriber to opt-in to those messages. Most countries and trade policies enforce some kind of anti-spam regulations, so recording the sources and activities of behaviors is critical. Here are the methodologies:
- Single Opt-In – This is the typical method for email and text message opt-ins. The subscriber signs up on a site or is imported by a company into a messaging platform. The advantage of single opt-in is in its simplicity, requiring no additional interaction. The downfall of single opt-in is that your form could be targeted and spam trap addresses automatically subscribed to your list. You can find your emails blocked down the road. The advantage of single opt-in is that users often opt-in for a subscription but won't take further action with double opt-in methodologies.
- Single Opt-In with Confirmation – This is a best practice for single opt-in message subscriptions but often overlooked. A nice welcome message that confirms that subscriber has opted in and sets expectations on how often messages will be sent and what value they'll bring the subscriber is a great strategy.
- Double Opt-In – All messaging platforms want you to utilize this methodology because it reduces any risk of spam complaints. The subscriber opts in via a form, import, or text message. That's followed with an immediate message to confirm the opt-in. If it's an email, they typically have to click on a link in the email. If it's a text message, they have to respond with a confirmation that they're opting in.
There's also some psychology involved with the double opt-in:
The double opt-in essentially boils down to the reciprocity principle, a basic law of social psychology that says in many social situations, we give back what we receive from others. Start the relationship by showing you respect the person — and the email address they give you — and you set yourself up for returns in both reciprocity and open rates.
This infographic from Salesforce, How Psychology Can Make Your Emails More Appealing, walks through each type of opt-in and discusses means of personalizing your email experience to increase engagement and reduce unsubscribes and SPAM reports. It also tackles personalization and optimizing subject lines for increased engagement.