Nerding Out on Double Opt-In vs. Single Opt-In

Written By Rebecca Luttrell
 

By Adri & Rebecca at Inbox Academy

Hey fellow email nerds 🤓 Adri here 👋

Recently, while compiling an annual report for an ecommerce brand, I noticed something interesting—our spam and unsubscribe rates had been creeping up. Not alarmingly so, but enough for me to start digging into the issue to see if we could resolve it.

Interestingly, some of these issues were cropping up during the Welcome Sequence, which also showed higher-than-usual bounce rates. Naturally, this got me wondering: would turning on Double Opt-In (DOI) be worth it?

What Are Single Opt-In and Double Opt-In?

Before we dive into the data, let’s make sure we’re all on the same page about what Single Opt-In (SOI) and Double Opt-In (DOI) actually mean.

  • Single Opt-In (SOI):
    With Single Opt-In, a subscriber is added to your email list as soon as they submit their email address via a form. There’s no need for them to take any additional steps to confirm their subscription.

    • Advantages: Simple and seamless for the user, which often leads to faster list growth.

    • Drawbacks: It can result in more invalid or fake email addresses on your list, potentially leading to higher bounce rates.

  • Double Opt-In (DOI):
    Double Opt-In requires an additional step. After someone submits their email address, they’re sent a confirmation email and must click a link to verify their subscription before being added to your list.

    • Advantages: This ensures the subscriber’s email address is valid and that they’re genuinely interested in your emails. This typically leads to higher engagement rates and better list quality.

    • Drawbacks: That extra step can deter people—20–40% of leads fail to confirm their subscription, which can slow list growth.

Now that we’ve laid the groundwork, let’s talk about the case for and against DOI and what the stats reveal.

The Case for Double Opt-In

Double Opt-In requires subscribers to confirm their email address via a follow-up email before being officially added to your list. It’s often praised for:

  • Higher Engagement: Subscribers who go through DOI are typically more engaged with your emails.

  • Cleaner Lists: It can prevent invalid or fake email addresses from bloating your list.

  • Better Deliverability: Cleaner lists mean fewer bounces, which can protect your sender reputation.

Sounds great, right? But there’s a catch...

The Downside of Double Opt-In

In my experience (and the stats back this up), 20–40% of leads fail to confirm their subscription when DOI is enabled. That’s a big deal, especially if growing your list is a top priority.

So, would the potential increase in engagement and reduction in bounces, spam, and unsubscribes outweigh the drop in new subscribers? It was time to dig into the data.

What the Stats Say

After some research, here’s what I discovered:

  • DOI increases engagement rates. Open rates and click-through rates (CTR) tend to be higher for subscribers who confirm via DOI.

  • DOI does NOT reduce unsubscribe or spam complaint rates. 🤯 This one surprised me! Even with DOI, you’re not immune to these issues.

  • Bounce rate comparisons were inconclusive. While DOI is assumed to reduce bounces, the data I found didn’t provide a clear verdict.

The Verdict: Single Opt-In Wins for Now

Ultimately, I decided against turning on Double Opt-In for this brand. Why? Their open and click rates were already solid, and the slight uptick in spam and unsubscribes didn’t warrant sacrificing list growth.

If list quality was a bigger issue, or if we were seeing major engagement problems, DOI might have been worth testing. But for now, sticking with Single Opt-In made the most sense.

What’s Your Take?

That’s my little adventure into opt-in strategies! Have you experimented with Single vs. Double Opt-In? Did you see a major difference in your email metrics? Let me know—I’d love to nerd out with you.

Until next time, keep those email campaigns humming! 😊

 
Rebecca Luttrell