Single opt-in or confirmed opt-in? Let’s thrash out the argument

Lately there have been several email opt-in incidents which have roused discussions among email marketers. The dotdigital Deliverability Team has addressed many questions about the subject, so we thought we’d take the time to dive a bit deeper into what opt-in or double opt-in (confirmed opt-in or COI) means for the industry.

First things first: what exactly is double opt-in email marketing?

Generally speaking, you’re given two options when setting up your email subscription list on dotdigital: single opt-in and confirmed opt-in (double opt-in):

  • Single opt-in: You offer the ability to subscribe to your email list on your site and a visitor decides that they wish to subscribe. They type in their email address and they’re automatically added to your list — no further action is required on their part.  You begin sending your campaigns to them and that’s that.
  • Double opt-in or confirmed opt-in (COI): You offer the option to subscribe to your email list on your site and someone uses that mechanism to subscribe. After they’ve entered their email address on your site, they’re sent an initial email asking them to confirm their subscription before they’re actually added to your list.  This affirmative action from the recipient is confirmation that they actually do want to receive email from you. Therefore, there’s essentially a two-step process to getting on your list.  If the recipient doesn’t respond to the initial confirmation email, they’re not added to the list and shouldn’t receive any further emails from you.

On the surface the single opt-in process seems like the best route to take. It’s quick and easy, and, let’s face it, some users are unlikely to respond to the confirmation email. That might be true but as far as single opt-in goes, there are several reasons why you may want to avoid using it and choose to move over to double opt-in.

The pros and cons of single opt-in list building

The pros

  • Single-step process: This is one thing that most of us could argue in support of single opt-in email marketing. We all want to make it easy and simple for our subscribers to join our mailing list. Since the single opt-in option offers the quickest way to subscribe, it does have the upper hand in that regard.
  • Build your list(s) faster: Leading off from the point above, since using the single opt-in option makes it easy for people to subscribe to your list, logic would lead you to think that this’ll help you to grow your email list faster.

The cons

  • Unwanted subscriptions (sometimes called spam subscribers): This downside of single opt-in single-handedly wipes out the two pros above. Let’s have a look at why this is a bad thing:
  1. If you’re offering an incentive to someone for providing their email address, you should be aware that there are plenty of people out there who’ll enter a fake email addresses (or even temporary email addresses) just to get access to incentive. This can mean huge issues for email marketers.  Not only will you be sending emails to non-existent mailboxes (maybe even spam traps), but you also have emails that are just wasting space on your list and possibly making you pay more for no reason.
  2. Yes, bots. There are bad actors out there who have created bots which search the Internet looking for email list subscription forms and pop-overs.  Once it finds them, it will add lists of email addresses (valid, live email addresses which belong to real people) automatically.  This means that recipients who never asked for your email at all will start to receive your campaigns, creating a huge risk for abuse complaints and mail being marked as spam/junk.
  • You can’t prove it: By this, we mean single opt-in doesn’t allow you to collect verifiable proof that someone has actually confirmed their wish to receive email from you, whereas double opt-in does. Proof is not only a good thing, but also a requirement of some anti-spam legislation (Canadian Anti-Spam Legislation or CASL). Looking forward into the future with the General Data Protection Regulation (GDPR), it’ll be extremely helpful to have a confirmation from the recipient to avoid any issues should the question of consent arise.

In summary, while single opt-in email marketing may have its upsides, the fact that it can be easily susceptible to fraud and abuse makes its value extremely low. As an email marketer, you want to send content to those who actually want to receive it (having a positive impact on opens, clicks, reads and purchases).  With single opt-in, you run the risk of sending to spam traps, bots, and/or persons who never signed up to your emails in the first place.  This could cause huge issues which would affect your reputation and cause severe deliverability issues.

Why is double opt-in email marketing better?

After reading about the downsides of single opt-in, you may have already started to shy away from this strategy. Just in case you’re not convinced yet, let’s take a closer look at why we think it’s better to use double opt-in for your email marketing program.

Let’s look at some numbers

A study conducted in 2011 took a look at the variables between double opt-in versus single opt-in marketing. The report revealed the following:

  • Double opt-in emails had a better open rate and saw a 72.2% increase on unique opens (emails opened which didn’t count multiple opens from the same subscriber).
  • Double opt-in lists saw a 144% higher open rate compared to single opt-in lists.
  • Double opt-in emails saw 48.3% lower bounce rate than single opt-in emails.
  • The unsubscribe statistics showed that double opt-in email rates were 7% lower than single opt-in emails.

These statistics are very telling. In just about every area that matters, the double opt-in email list performed leaps and bounds better than its single opt-in counterpart.  The bounce rate and open rate seem to be the most alarming in terms of differences in how the two perform. This study shows there are huge advantages to using double opt-in for your email marketing program.


To sum it all up, a single opt-in option may allow you to grow your list faster, but the quality of your list and your email marketing efforts as a whole will probably be adversely affected.  Not to mention spikes in unsubscribes and abuse complaints (and even worse, blacklistings), which will negatively affect your email reputation, your brand reputation and could ultimately cause suspension of your dotdigital account.

I hear a lot of marketers say they shy away from double opt-in because they feel that “extra step” causes too much trouble for the recipient, so they feel they just won’t take the action.  If you think about it, the people who opt-in for your email are most likely already sitting at their computer or have their mobile device with them, which means that their email is there too.  It’s just a couple of clicks away, and if they go to their email and confirm their subscription, then chances are they really do want to be on your list. .  If they decide not to confirm their subscription, you may be losing a subscriber, but you’ve likely just saved yourself from a fraudulent sign-up or spammer who didn’t really want to be on your list in the first place, thereby dodging a bullet.

Either way you look at it, you come out the winning end and you’ll be building a high-quality list which is where the money really is when you utilize double opt-in!

You can find out more about using double opt-in (COI) via our dotdigital support portal.

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