Search “Double opt-in” in Google, and you’ll get over nine million hits! Clearly, a lot has been written on the subject. Nine million results, a large part of which are composed of questions like “Should I use a subscription confirmation?” and “Double opt-in or single opt-in?”…which leads us to believe that there is still a great deal of doubt about whether this technique is really necessary.

And with GDPR knocking on our front doors and some ESPs deciding it is time to move to single opt-in, we think it’s time for you get the facts and learn why, at Mailjet, we strongly believe double opt-in is the best way forward.


What is double opt-in?

When your 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. Double, because there is a first authorization at the time of registration and a second one, with the confirmation email. Let’s take a look at what this looks like…


Skyscanner opt-in


Skyscanner’s Price Alert form allows you to check a box to subscribe to their email communications.


Once you’ve filled in the form, Skyscanner follows up with a confirmation email, asking you to click on a link to confirm you want to receive their Price Alerts. In this email, they clearly specify what you can expect from their email communications, and what you need to do if you don’t want to receive any more emails from them.  

The advantages of double opt-in

Double opt-in allows you to be sure:

  1. That the email address is valid;
  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.

These three advantages allow you to begin your relationship with your subscriber on good terms:

  • He/she agrees to receive your newsletter; he/she even agreed to it twice. Thus, the subscriber will not classify your emails as spam later on down the road.
  •  By requesting that he/she clicks on the confirmation link, you have already generated your first interaction with your subscriber. This is a positive sign sent to the webmails and a good start for your sender reputation.
  •  You avoid sending your newsletter to an incorrectly typed email address. This will prevent you from having to clean up your list later. Although we recommend cleaning your list every few months to keep engagement as high as possible.

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


The new double D: Double opt-in & Deliverability

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 (and even ESPs) that favour 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 improve 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. If you send from a dedicated IP, all of these are key signs for ISPs that will increase your sending reputation and your chances of landing in the inbox.

While not all ESPs do, at Mailjet we strongly recommend double opt-in for those sending from shared IPs too. At the end of the day, every email campaign send to any contact list in a shared IP contributes to its sender reputation, and as a leader in good deliverability we want to ensure all of our users have the best possible chances of reaching the inbox. We don’t want any of our shared IPs blacklisted, do we?

Double opt-in- Should I or Shouldn't I?


Have any more questions about double opt-in or how it can impact your deliverability? Don’t hesitate to reach out to us on Twitter!



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 13th, 2013.