The Big Difference Between Single and Double Opt-In


The term Opt-in describes the process of signing up users to receive further correspondence from you or your business. In other words each user on your list actually wants to be on your list, meaning they have indicated they want to receive specific content from you.

The double opt-in versus single opt-in methods of registration indicate how many times a user must confirm their interest, so to speak.

In a single opt-in, a user can enter their email address and receive correspondence straight away. This differs from a double opt-in, which requires users to enter their details and then confirm their address, via a unique link sent to their email address.

A double opt-in email approach is seen, in most circles, as a tidier method of registering users as you’ll always be certain that you’re sending to a real person and not a bad email address.

The single opt-in option leaves the door open for third parties and casual sign ups to mix amongst genuinely interested parties, reducing the overall effectiveness of targeted campaigns.

Although a single opt-in list will likely grow (20-40%) faster than a double opt in email list, campaign reporting results often plummet due to a lower level of subscriber engagement - specifically resulting in:

  • Lower open rates
  • Lower click rates
  • Higher bounce rates
  • Higher unsubscribe rates
  • Possible spam complaints

By skipping the process of confirming an address, an email marketer has forgone a very important indicator of future campaign success.

Why choose double opt-in? 

  1. Fewer complaints
    A double opt-in email user is less likely to report a sender’s message as spam unless your messages make it difficult for them to opt out. And when enough email addresses report your messages as spam, your sender reputation can be called into question - ISPs take this data under advisement when deciding whether or not to push your messages to a recipient’s junk folder or deliver to their inbox.

  2. Increased engagement
    While mulling over which type of opt-in method to use, it’s always worth remembering that the aim of the game should always be engagement. A double opt-in can better ensure users will open an email, click through, and purchase a product or service because they have confirmed their interest, your deliverability skyrockets and you will likely see the results manifest elsewhere, such as in sales.

  3. Less spam traps
    Sending emails to unengaged users is prime spam trap fodder. And unless of course you’re not cleaning out your lists regularly, the likelihood of you having spam trap emails on a clean list reduces drastically or is non-existent. Getting rid of hard bounces and evidently unengaged parties not only returns better results, but keeps ISPs from putting a target on your back. It’s also worth noting that a sure fire way to lower the odds of becoming the target of a spam trap is to avoid purchasing lists in any instance.

  4. Better odds of landing in the inbox
    The sweet spot of any email marketer is the inbox, and a double opt in method is essentially calling for subscribers to interact with your mail, which further indicates to ISPs that the user would likely benefit from continuing to receive such messages.

So you’re currently using a single opt-in list
Working with an existing single opt-in list isn't entirely a bad thing, and can work for some companies. Your lists may just need a little more grooming and refining that some lists. A lot of hard bounces, unsubscribes, and increasingly low open rates, indicate that your list is stale, and you have potentially abandoned and uninterested addresses that need to be removed from an otherwise active list. ISPs closely monitor emails sent to invalid addresses, so ensuring you have an on-going sunset policy can help maintain sender reputation and ensure delivery of your campaigns.

If you don’t want to let inactives go just yet though, consider a reactivation campaign. The purpose of a reactivation campaign is to reconnect with users whose engagement numbers have dipped below desirable levels. Sending emails to confirm they are still interested in receiving correspondence does the job of a double opt-in.

It’s also worth noting that mixing single and double opt-in lists on the same IP address should be avoided. Because of the varying nature of these methods, a clean double opt-in email list may suffer because a single opt-in list falls prey to a spam trap or low engagement. A dedicated IP is best practice, especially in the case of high volume senders. Learn more about dedicated vs shared IPs for optimal email marketing.

Best practice also favours sending a welcome email along with sign ups, regardless of whether they’re single or double opt-ins. A good welcome message will likely include things like the user’s name, a brief message thanking them for confirming, and further promotion or instructions if any. This is common practice but also acts to identify addresses that bounce back so that they can be promptly removed from any active lists.

A good opt-in strategy can be the difference between a list that works and a list that doesn't. Closely monitoring how well an email list is performing is essential. A double opt-in practice can help improve the quality of a mailing list, ensuring that only those who truly want to receive correspondence do. To improve the overall effectiveness of a campaign, consider a double opt-in approach.