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Single vs. double opt-in: Which one should you use?

Discover the differences between single and double opt-in and why you should use it in your email marketing. Solve all your doubts by discovering the advantages of using double opt-in.

Hermes on a moped delivering mail to a mailbox



If you’ve been using single opt-ins for a while, the idea of double opt-ins may seem a little daunting. You’re effectively doubling the number of steps a user takes before their added to your lists.

And this can be a little scary for most email marketers whose KPIs are growth driven. There’s no room for thinking about some of the technical aspects behind email marketing like deliverability and sender reputation.

That’s why today, we’re explaining how cultivating quality over quantity can save you more time and energy in the long run. We believe having a healthy list of engaged subscribers trumps having unvalidated emails land added to your lists every day.

So without further ado, let’s double down on the practice of double opt-in.

What is double opt-in?

Double opt-in is the process of obtaining explicit consent from a user to receive emails. An automated confirmation email immediately arrives after the recipient signs up. This confirmation message typically includes a verification link or code that the user must click on or enter to confirm their subscription. This ensures the user is real and has willingly agreed to receive communication from the sender.

But how does this differ from other methods? When users subscribe to your email marketing program via a registration form, you have a choice. You can welcome them and start sending them newsletters right away –which is what we call single opt in –or you can ask your contacts to confirm they want to receive your email communications by sending them an email with a confirmation link. It is this latter possibility that we call the double opt-in. It’s double because there is a first authorization at the time of registration and a second one with the confirmation email.

Double opt-in allows you to be sure:

  1. That the email address is valid with no typos

  2. That the owner of the email address is really the person who subscribed to your mailing list

  3. Your new contact is really interested in receiving your communications and is more likely to engage with your content

Skyscanner’s example below is a perfect example of a double opt-in registration in action. Once you’ve filled in the form, Skyscanner follows up with a confirmation email, asking you to click on a link to confirm that you want to receive their price alerts. In this email, they clearly specify what you can expect from their email communications and how to opt out.

Skyscanner price alert opt-in form and confirmation email

Skyscanner’s Price Alert form allows you to check a box to subscribe to their email communications. Then, Skyscanner sends a confirmation email to weed out bots and incorrect emails.

In summary, the double opt-in process allows you to obtain a more qualitative and proactive list of subscribers who are really looking forward to your content. Who could ask for more?

The double opt-in process

Unlike a single opt-in process which requires only one or two steps, the double sign-up process contains double the number of steps to complete for the user.

The double signup stages are:

  1. Signup form: User fills out a form with their personal information, such as name and email address, on a company's website or landing page.

  2. (Optional) Thank you page: thanking the user for handing over their information and telling them to check their inbox for a confirmation link.

  3. Confirmation email: A short email from the company that includes a link to confirm their subscription (examples below).

  4. Confirmation page: The page users land on should inform the user that they have successfully been added to the list after clicking the confirmation email link.

As you can see there are several moving parts to this signup process which can be off-putting for some marketers. However, we’ll try to convince you it’s all worthwhile by covering the advantages of the double opt-in.

Single vs double opt-in

Tread carefully – choosing between single and double opt-in has significant repercussions for your email program. But there’s no right and wrong here. However, you need to determine which is right for the current state of your organization and the customers you’re dealing with.

While weighing up the pros and cons of each signup process, think about how each choice will affect the user experience, your relationship with inbox providers, and overall engagement metrics.

Pros and cons of single opt-in




  • Quic­k and easy­ for user­s to comp­lete

  • High­er numb­er of inva­lid or frau­dulent emai­l addr­esses lead­s to lowe­r deli­verability rate­s


  • Resu­lts in a high­er numb­er of subs­cribers

  • Emai­l list­s will­ need­ to be clea­ned freq­uently to avoi­d dama­ge to send­er repu­tation

  • Redu­ces fric­tion in the user­ expe­rience

  • Incr­eases the risk­ of bots­ or mali­cious acto­rs abus­ing the syst­em

Pros and cons of double opt-in




  • Ensu­res that­ only­ vali­d emai­l addr­esses are prov­ided

  • User­s may find­ the proc­ess more­ cumb­ersome or time­-consuming, lead­ing to lowe­r conv­ersion rate­s


  • Help­s to fost­er a more­ enga­ged audi­ence

  • Resu­lts in a lowe­r numb­er of subs­cribers as some­ user­s may not conf­irm thei­r subs­cription

  • Less­ list­ clea­ning requ­ired

  • Adds­ fric­tion to the user­ expe­rience

  • Util­ize opt-­in enga­gement to onbo­ard cust­omers

  • Extr­a cons­ent safe­guards agai­nst chan­ging data­ poli­cies

Hopefully by now the strengths and weaknesses of both strategies are clear so you can make a conceited decision. If you go for the double opt-in, we have some great examples of companies that have pulled it off successfully.

By implementing double opt-in and following up with a welcome email or sequence, you can establish trust, build credibility, and set clear expectations with your subscribers, ultimately leading to higher open rates, click-through rates, and conversions.

The advantages of double opt-in

Yes, we know there’s more work involved, but the payoff for using double opt-in is equally attractive. Let’s go through the many advantages.

Create self-cleaning lists

Your lists are constantly getting dirtied by incorrectly typed addresses, changing job roles, or just plain trickery. This is why list cleaning is one of the most fundamental best practices of email marketing. It ensures your stats are accurate and keeps you in the good books of mailbox providers like Gmail and Outlook.

Drive higher engagement

By asking users to verify their email, you have already generated the first interaction with your subscriber. This is a positive signal to the mailbox providers and a great start for your sender reputation.

Plus, when they agree to receive your newsletter, they have agreed to it twice. Thus, the subscriber is less likely to classify your emails as spam further down the road.

So on the surface, you may appear to have fewer total subscribers in your database, but your engagement levels will be higher and more accurate without an unengaged portion. This makes your reporting dashboard and decision making more accurate.

Using double opt-in means you avoid sending your newsletter to an incorrectly typed email address and prevents you from having to clean up quite as often. Although, we still recommend cleaning your list every few months to keep engagement as high as possible.

Bolster deliverability and IP reputation

If we look at the reality of the situation, the popularity of the double opt-in has increased significantly, but there are still some senders that favor single opt-in.

While some might think double opt-in is an unnecessary step that will make it harder to get email addresses, it should not be seen as a barrier between the user and your company. Having a more engaged contact list is key to improving your deliverability.

A user that really wants to receive your content is more likely to engage with it, which will improve your open and click-through rates. It will also mean you don’t get any undesired email addresses in your contact list, mitigating the risk of falling into a spam trap or being marked as spam.


Landing in the inbox: Email marketing deliverability basics

Don’t let great emails go to waste. Discover everything you need to know to land in the inbox.

Generate marketing qualified leads

A company’s time is valuable and bad lead equals money wasted. Every time a potential customer interacts with your company, they’re warming up into a qualified lead. If signing up for a newsletter, ebook, or webinar is considered to be a warm lead, then clicking a double opt-in email moves them into the hot category.

This method is especially useful for higher quality gated content like reports which take a lot of resources to produce. Quite often, some users deliberately enter invalid data to get access to gated content on the website. But by having the report sent via a double opt-in process, bad actors cannot get access without a legitimate email address.

Future proof from data policy

While double opt-in is not currently a legal requirement for Europe’s General Data Protection Regulation (GDPR) laws, having extra proof of consent is highly advantageous. The law states that personal data must be “freely given, specific, informed, and unambiguous.”

Privacy laws are always evolving, so collecting extra consent could save you from having to verify records further down the line, as many companies did with GDPR. For example, courts in Austria and Germany have already ruled double opt-in as a legal requirement in certain cases.

Adding double opt-in also means you keep your initial subscription form simple and free of checkboxes. The legal opt-in message and CTA can be shown during the activation email. This makes the journey for the user more like a funnel and could well lead to higher conversions.

Start the onboarding experience

While users must jump through more hoops to get on your list, double opt-in emails are a great opportunity to kickstart the onboarding experience. It’s not often you’ll get higher open rates than a double opt-in email, so it’s wise to take advantage of the extra traffic.

A confirmation email is usually just a link with a CTA, but it could serve as an introduction to your brand personality. For example, instead of saying, “Confirm your email to get started,” you could say, “We’ve been expecting you!” But at this point, it’s best to keep the recipient focused on just one CTA.

That is until they get to the confirmation page on your website. This landing page can serve as a chance to link to some pages on your site that are perfect starting points for new users. This could include education on how to use your product, popular blog posts, or a guided tour of the site.

Double opt-inspiration

We’ll admit that most email confirmations are pretty basic and transactional in nature. And while there’s absolutely nothing wrong with that, we’d like to highlight some of the more creative double opt-in emails sent out over the years. After all, first impressions count and this email will be seen by a large portion of your email list. Let’s take a look at these opt-inspirational emails.

The arty one

Nothing quite grabs the eye like a well-designed email with sharp contrasting colors. Stocksy United achieves that with their mystical purple and black shaded email featuring a peculiar cable cladded human at a desk. It is true that sometimes opt-in emails get missed. So creating something eye-catching might just convert a few subscribers who might miss the email.

Cable man sitting in chair

Rather than getting lost in the art vogue, there’s a large heading saying, “Confirm Your Account” to keep the reader’s eye on the prize. It’s worth noting that this method uses a verification code instead of a CTA.

The illustrated one

Waze uses its brand colors to create something truly welcoming for its new subscribers. This illustrated email screams “welcome to our email list” with its sunny rolling hills.

Not just welcoming, there’s a little message below the CTA telling the reader what to expect. Opt-in emails are a great chance to educate people about your product offering, especially in small parts.

Message with green rolling hills backdrop

Waze provides a short but very useful confirmation email.

The welcome message

Last but not least we have a double opt-in message from Medium. We love this one as it uses the power of copywriting (which is their platform offering) to offer a little welcome message to their readers.

Within the welcome message, there are plenty of indicators of their brand personality. Words like “welcome” “play” and “connecting” all tell the story of a company that cares about its audience.

Message with minimalist design

Also it’s worth noting that many senders choose to add a message below the main CTA in case the wrong address was entered. In this case, they ask the recipient to send an email to a support address.

Create double opt-in forms with Mailjet

Hopefully it’s clear by now whether you want to go for a double or single opt-in when signing up new subscribers. For us at Mailjet, we always recommend the route which leads to better deliverability, so we advise opting for the double opt-in.

Whatever your choice, Mailjet’s powerful Form Builder allows you to create the whole process from start to finish to onboard new subscribers to your list. Designing beautiful forms and emails is easy with the intuitive drag-and-drop designer.

Automating your opt-in workflow has never been easier, so give it a try for free today!

Form builder

Convert visitors with our subscription form builder

Create your subscription form using our drag-and-drop designer and grow your contact lists. Mailjet’s Form Builder offers a native double opt-in which guarantees your recipients' interest - an essential prerequisite for your reputation as a sender and GDPR.


This blog post is an updated version of the post “Double Opt-In: Should I Or Shouldn't I?", published on the Mailjet blog on September, 2013.

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