Double opt-in for emails: Best practices and examples 

Emails should never be sent to people who didn’t sign up for them—that’s a sure way to get your messages marked as spam, which can eventually tank your domain reputation. Double opt-in helps ensure your readers have wholeheartedly agreed to receive your messages, which produces increased deliverability, higher engagement, and better conversion rates.

Single opt-in is a quick, one-click affair, so why introduce an extra step with double opt-in? After all, if someone signed up for your mailing list, isn’t that enough to show they want to hear from you? Well, probably—but that’s not the whole story. People may sign up to get a freebie or discount but have no interest in further content; they create the illusion of good prospects, but tend to go poof as soon as the gravy train is gone. People also make typos, putting undeliverable emails onto your list, or sign up by mistake when they’re not paying attention (thanks, autofill). Even worse, malicious actors use bots to flood junk emails into forms, which can damage your list’s integrity and your domain reputation. Sending a double opt-in email after signup avoids these kinds of problems.

Bottom line: entering an email address into a form doesn’t guarantee enthusiastic consent. While double opt-in might mean you lose some people who don’t take the extra step of confirming their sign up, the benefit to the health of your email list is worth it. In this guide, you’ll learn double opt-in best practices (with handy opt-in email examples!) to help you optimize your deliverability.

Double opt-in is the practice of sending a confirmation email when someone signs up for your mailing list. They won’t be officially added to the list until they click a confirmation link in the opt-in email.

There are a wide range of situations in which someone might sign up for your marketing messages:

• Subscribing to your newsletter.
• Downloading a freebie.
• Getting a coupon code.
• Starting a free trial.
• Opting in when they check out.

In each case, a double opt-in process asks them to verify their action before they’re placed in marketing campaigns.

The difference between single opt-in vs. double opt-in comes down to the opt-in email. With single opt-in, someone just needs to enter their email address to subscribe. If you’re using double opt-in, that subscriber will receive an email verifying that they really want to sign up—if they don’t confirm, they’re not added to the list.

Many brands send a confirmation email letting people know they’ve signed up, even if they’re using single opt-in. But that’s only a double opt-in email if it contains a link the recipient must click to get on the list.

Double opt-in emails aren’t required to comply with regulations like CAN-SPAM, CASL, and GDPR. That said, double opt-in is legally required in a few countries: Austria, Germany, Greece, Switzerland, Luxembourg, and Norway. And the last several years have seen an increase in both governmental regulations and industry policies around personal information and privacy, so there’s always a chance that marketing opt-in requirements will become more closely regulated going forward. But even though double opt-in isn’t usually mandatory, it’s one of the best practices for your compliance and deliverability strategies. 

The downside of double opt-in is the friction it introduces into your sign up process. Customers must take an extra step, and you’ll inevitably lose some people. So, if you don’t have to send an opt-in email, what is double opt-in’s purpose? At the end of the day, it helps your marketing campaigns land in customers’ inboxes and get high engagement. And the best double opt-in emails cultivate a relationship that moves people toward your big-picture goals: conversion, retention, and long-term loyalty.

Two of the fastest ways to lower your deliverability rates are sending undeliverable emails and having your messages marked as spam. Double opt-in best practices help you avoid both.

• Cleaner lists: If a customer enters the wrong email address (or your form is hit with a bot attack), you’ll get hard bounces when sending messages. That can tank your overall deliverability (and leave you with a lot of manual clean-up work, too). Double opt-in keeps those invalid addresses from getting onto your list in the first place. 
• Fewer spam complaints: People who don’t actually want your emails are more likely to mark them as spam. That includes folks who just signed up for a one-time benefit, like a freebie, as well as those who subscribed by mistake or were added in a bot attack. Clicking the flag button in the inbox is a lot faster than opening an email to find the unsubscribe link. The more often that happens, the more likely email clients will be to see all your messages as spam and start sending them to the junk folder. 

Emailing someone who doesn’t care about your messages wastes time, money, and resources. Even if they don’t flag your emails as spam, they’re likely to just delete them or leave them unread in their promotions folder. A double opt-in email helps you focus your efforts on people who are more likely to engage.

• Ensure genuine interest: People sign up for mailing lists for all kinds of reasons: to get a discount, download gated content, or use a free trial. It would be nice if all those customers were really into your brand, but the fact is, it’s a one-and-done interaction for some people—however, those who respond to your double opt-in email signal that they’re truly engaged. 
• Start a relationship: Depending on your marketing strategy, someone who signs up for your mailing list might not hear from you for a while. By the time you reach out again, their interest may have waned—or they could have totally forgotten they joined your list at all. Double opt-in email marketing is a way to welcome new subscribers and begin building a relationship from the first moment they engage with you—plus lead them to the next step in their customer journey.

Think of double opt-in as a little voyage. Your customer’s action—signing up—starts it off. After that, you take them through a process to complete that action. To make it work, you need four interconnected elements.

Any page a potential customer regularly visits, such as your homepage, sales pages, and checkout pages, could include a signup form. You might also offer gated content, like whitepapers or eBooks, that people can download by entering their contact info. In addition to asking for an email address, consider including fields for other demographic data you could use for personalizing future campaigns, like name, location, and interests.

Once someone fills in the form, the signup confirmation page or pop-up must clearly state that further action is required. Otherwise, they might not realize they haven’t finished signing up, and you’ll miss the opportunity to bring a genuinely excited customer into the fold.

You’ve set expectations for the customer, so they’ll be anticipating your email. Trigger it immediately; any delay just adds to the friction. This communication is the crucial step in your double opt-in process, so pay particular attention to the content. Email opt-in language should focus the recipient’s attention on the one action you want them to take: click the button to confirm their subscription.

While this is also a great moment to roll out the welcome mat with a friendly message and branding, don’t let it distract from the CTA. Both your email opt-in language and design should reduce friction and inspire action! In this example, the double opt-in email is providing the customer with the gated content they’ve requested—giving them a compelling reason to click through.

When your new subscriber clicks the confirmation link, close the loop with a confirmation page. This not only affirms that they’ve subscribed, it’s also an ideal moment to drive the relationship forward. Provide a next step that nudges the customer into deeper engagement, like asking them to fill out their profile, giving them a discount code, or offering up useful content. And since they’ve just opted in to hear from you via email, it’s also a great time to invite them to connect with you through other channels, like social media or SMS.

Opt-in email marketing can be a powerful pathway to better engagement. To make the most of it, treat your opt-in emails with as much care as your other marketing campaigns. The opt-in email is the very first time you’ll show up in people’s inboxes—so make a great impression by following double opt-in best practices.

The best double opt-in emails create a cohesive experience. Your new subscriber has just visited your website, where your brand identity is on full display. They should encounter the same look and feel when they open your opt-in email. Your logo, colors, and font choices should all make the message feel like an extension of the signup process they’ve started. And ensure your email opt-in language infuses your brand’s voice without sacrificing clarity. The same goes for confirmation pages—everything should feel like a unified journey.

Opt-in emails are an example of transactional messages: communications that provide essential, expected information a customer actually needs to interact with your brand. That’s why they don’t require an unsubscribe link (which would be redundant for an opt-in email anyway, since the recipient hasn’t fully subscribed yet). Including anything promotional moves your message into marketing territory, which is likely to violate trust and distract from the crucial action the recipient must take to finalize their signup. 

With the rising popularity of SMS marketing, many brands now encourage customers to sign up to receive text messages as well as emails. With this omnichannel strategy, using a double opt-in process for SMS is just as important as double opt-in for emails. And in both cases, personalization can drive higher engagement. This is where a thoughtful approach to your signup form is vital: it’s a chance to gather customer data you can use to make your messages feel personal to each individual. Simply collecting a name along with contact information lets you customize your opt-in email’s language with a subject line and greeting that includes an individual’s first name. And if it makes sense for your brand, consider asking what topics someone’s interested in when they sign up—you can use that to provide tailored content and next steps on your opt-in confirmation page!

If you’re considering a double opt-in strategy, think ahead so it’s in place at the right time. Most brands increase their send volume around important events or seasons. A spike in sending can put email clients on spam watch, and if your list isn’t healthy at that time, you’re at even higher risk for deliverability problems. Identify when you expect to send a larger volume of email in the coming year based on your business cycle and industry. E-commerce brands, for example, often see Black Friday deliverability issues due to industry-wide increased email volume. Or consider SaaS platforms: a major product update will call for a spike in sends—often multiple emails to all customers. In other industries, common drivers for high send volume are major conferences, product launches, rebrands, and holidays. Get your opt-in email marketing in place now so you’re prepared. 

If you’ve been using single opt-in vs. double opt-in, you already have a list of subscribers. You don’t need to send them a double opt-in email; you can safely assume they’ve consented to receive your marketing messages. However, the deliverability benefits of implementing double opt-in can be undermined if your existing list is full of disengaged customers. So consider sending a re-engagement email to inactive subscribers now and implementing an ongoing re-engagement strategy and sunset policy to keep your list healthier long term. Pro tip: build a subscription center where people can choose what kind of emails they want to receive, and invite them to set preferences for the type of content that’s relevant to them.

Now that you know the ins and outs of opt-in email marketing, it’s time to get inspired! The following opt-in email examples showcase some of the double opt-in best practices to give you ideas for building your own successful campaign.

Tome (an AI-powered research and presentation SaaS platform) nails the all-important clarity aspect of opt-in emails. Every element of the email opt-in language—subject line, headline, body copy, CTA button—drives toward a singular objective. But that doesn’t mean they skip brand messaging entirely. A prominent logo and supporting text at the end remind subscribers who the brand is and the product’s value, giving them a reason to click that confirmation button!

Headspace (a meditation and mental health app) gets two things very right in this opt-in email: personalization and support. By including the recipient’s organization and email address (smart to collect both at sign-up!), they leave no doubt in the customer’s mind that this is a legitimate message they need to respond to. And Headspace also anticipates a potential friction point in the double opt-in process: the odds that a customer doesn’t check their email right away. Below the CTA button, there’s an easy path to completing enrollment if the customer hasn’t responded in 24 hours—no dead end here!

Who says your double opt-in email can’t double as a welcome email? As long as the welcome message doesn’t get in the way of the email’s opt-in language and CTA, this can add a nice bit of relationship-building (though if you go this route, consider A/B testing to make sure it works for your audience).

Honeygain (a fintech app that lets people make passive income by sharing their internet bandwidth) takes a balanced approach by putting the verification step front and center, driving the customer’s attention to the critical action needed now. But they follow it up with robust content to walk people through what they should do next, allowing the opt-in email to serve as a useful reference to begin the onboarding process. Notice that they manage to do all this without veering into promotional messaging: everything is need-to-know info for customers to use the app.

Ready to start building your opt-in email marketing campaign? Let’s walk through how to send an opt-in email with a triggered campaign in Customer.io Journeys. If you already use Journeys as your automated messaging platform, you can just hop into your account and use this workflow as a template. And if you’re not a subscriber yet, this will show you the steps you’ll need to include in a campaign (or perhaps you’d like to start a free trial so you can give it a whirl!).

Use the sign-up form on your site to trigger a campaign in Journeys. The trigger can be that a person completed the form (event-triggered) or a set of conditions that match once a new profile is added to your system (condition/segment triggered). The campaign sends a double opt-in email to the customer immediately.

Next, follow double opt-in best practices to craft a clear and compelling opt-in email and add it to your campaign. The opt-in email examples above should give you plenty of fodder for inspiration.

There are two outcomes for your opt-in email: the customer confirms their subscription or they don’t. You’ll want two branches in your campaign to address both scenarios.

If they confirm: Once customers click the email confirmation button, their unsubscribed attribute will update to “false” if you use Customer.io’s global unsubscribe link. Alternatively, you can add a custom attribute “has_confirmed_subscription” to track whether or not a customer has subscribed. And for the best customer experience, you can set up a subscription center, allowing your customers to opt into specific topics that are most relevant to them.

If they don’t confirm: You don’t have to give up on a subscriber if they don’t respond to your opt-in email—you can give them a second chance! If the customer doesn’t click the confirmation button in the email, send a reminder two days later. When they convert from that email, update their unsubscribed attribute to “false”. But if there’s no response to the second opt-in email, it’s best to remove them from your list, so you’ll update their unsubscribed attribute to “true”.

Here’s what the campaign looks like in the Journeys visual workflow builder:

Once a customer has confirmed their subscription, they move into a triggered welcome campaign, which seizes the opportunity to build on their current enthusiasm to deepen engagement.

When customers take the time to sign up and affirm their interest, they’re giving you a powerful signal that they want what you have to offer. Don’t leave them hanging! A double opt-in email might be an extra step, but it can also be valuable for both you and your customer. It’s a benefit for your deliverability and engagement and also an invitation for a new subscriber to start getting to know you better.

In fact, your opt-in email can be seen as the beginning of your lifecycle marketing strategy: the first moment to lead customers down the path of long-term engagement. Think about the next meaningful milestone, and use your confirmation page to guide people toward value-added experiences.

Setting up double opt-in is fairly straightforward, and the payoff can be tremendous. It’s one of the foundational principles of high deliverability. Want to learn the other secrets to reliably landing in customers’ inboxes? Check out our deliverability workshop!