Opt-in Email Marketing Guide: Tips for Opt-in Email Campaigns

Opt-in email marketing helps you send messages to customers you know are interested in hearing from you. Potential customers opt into receiving emails from you, usually through a sign-up form, landing page, or subscription box, in exchange for updates, offers, or other content.

Getting your opt-in process right helps you improve email deliverability and remain compliant with privacy laws, such as the European Union’s 2018 General Data Protection Regulation (GDPR).

Ahead, learn more about what opt-in email marketing is, see examples of opt-in forms, and read about best practices for creating your own. 

What is opt-in email marketing? 

Opt-in email marketing is a strategy businesses use to collect contact information from site visitors. A type of permission marketing, opt-in email marketing relies on getting explicit consent before sending communication. For example, if you’ve ever entered your email on a company’s website to “Get Updates” or “Unlock 10% Off,” you’ve participated in opt-in email marketing.

Customers can opt into your emails when they add their email address to a newsletter sign-up box, when they sign up to receive an offer like a welcome discount, when they enter their email during the checkout process, or when they create an account. In the latter two cases, it’s best practice to secure explicit consent by having the user check a box indicating they agree to receive marketing messages from your brand. For companies who do business in Europe, that’s required by the GDPR.

Opt-in email sign-up forms let you send messages to engaged shoppers who’ve shown interest in hearing from you. With cold emails, or messages to email lists that you purchase, potential customers receive messages they never signed up to receive. In Europe, sending cold marketing emails without explicit consent is prohibited. 

Once you have a list of interested consumers, you can reach them with an email marketing software like Shopify Messaging, a native Shopify tool.

Single opt-in vs. double opt-in 

When someone enters their email address into your opt-in form, there are two ways for them to become subscribers.

• Single opt-in: The subscriber provides their email, then you add them to your list

Double opt-in: After the subscriber shares their email address, you send them a follow-up email or text message to verify that they want to be on your list.

If your goal is to create an engaged email list, the double opt-in process is a best practice. If you do business in Europe, it also helps you meet GDPR requirements, and may be necessary for subscribers in Germany.

Double opt-in requires subscribers to take an additional step, but that doesn’t bother most consumers: 32% like it, another 32% don’t mind it, and only 8% actively dislike it, according to Mailchimp’s 2026 The Art of the Opt-In report.

Here’s an example of a double opt-in confirmation email from the online vintage shop Justin Reed. The message tells readers why they’re receiving the email and what to do in order to subscribe. 

Source: Justin Reed

You can add double opt-in to your Shopify site from your admin. Navigate to Settings > Notifications > Customer notifications. In the Marketing double opt-in section, select Customer marketing confirmation. If you use another app or service to manage subscribers, you may also have to activate double opt-in within that app.

Best practices for opt-in email campaigns

• Make an offer
• Get consent
• Prevent bot sign-ups
• A/B test your CTAs and offers

Here are four of the best opt-in email practices to create an engaged list of subscribers.

Make an offer

Sharing an offer gives potential subscribers a reason to sign up for your emails. 

“We’ve seen that just by adding a discount code to get that email for their first order, the conversion is huge,” Julie Brown, co-founder of clothing brand Province of Canada, says on Shopify Masters. “It seems simple, but it really does work.”

Here’s an email opt-in pop-up from Province of Canada with an offer for 10% off your first order. If you run a Shopify store, you can create email marketing popups like this one by adding the Shopify Forms app to your online shop.

Get consent

For legal and privacy reasons, make sure your customers agree to receive your emails. In other words, get their explicit consent. 

In an email sign-up module, make it clear they’re signing up for marketing emails. When collecting an email during checkout or account creation, have the user opt into marketing emails via a checkbox and/or confirm their subscription through double opt-in. 

While opt-in consent isn’t required in the US, it is required by the European Union’s GDPR. The GDPR also governs other aspects of email marketing practices, so make sure you’re familiar with the requirements if you sell to customers in Europe.

Here’s an example of getting explicit consent from children’s book company MiJa Books. The company uses a giveaway landing page as an opportunity for potential customers to opt into marketing emails. The checkbox next to “Sign Up For MiJa Books Newsletter & Communications” lets entrants consent to receiving marketing emails from MiJa Books.

Note that in the US, you may pre-fill the box asking for consent. In Europe, under the GDPR, you cannot pre-fill the checkbox. 

If you’re on Shopify, you can turn on opt-in email marketing at checkout and sign-in, and Shopify will display a consent checkbox to customers. You can decide whether or not to leave it preselected, and in which regions. 

Here’s another example of asking for explicit consent from online boutique Lisa Says Gah. When shoppers enter their email address at checkout, they see a checkbox that reads, “Email me with news and offers.”

Once you’ve captured subscribers’ email addresses, be sure to protect their privacy. The native Shopify Messaging platform has built-in privacy features. Read Shopify’s privacy and data protection guidelines to learn more about protecting your customers’ data.

Prevent bot sign-ups

Bots can submit fake email addresses through your website forms. These sign-ups can hurt your email deliverability, by lowering engagement and increasing bounce and spam complaint rates.

To prevent bots from adding email addresses, hCaptcha is activated by default on all Shopify stores. HCaptcha is a technology that detects bot activity. Double opt-in can also help eliminate bot subscriptions, because subscribers will need to manually agree to receive your messaging a second time.

A/B test your CTAs and offers

A/B testing is when you compare two versions of the same element to see which one is more successful in generating a result like conversion rate. For example, you might test two CTAs with different wording, or different placement in an email. 

Test different versions and placements of your email sign-up module to see which performs best. Experiment with different offers, messaging, designs, and on-page placements. If you’re on Shopify, you can use A/B testing apps to compare different email capture modules on web pages. 

If you use a third-party app like Klaviyo or Mailchimp to create email capture popups, you can use those softwares to conduct A/B testing on your pop-up forms.