October 24, 2018

Deliverability 101: Two is better than one (when it comes to opt-in practice).


How do you know someone wants to receive your email? They’ll need to opt-in, of course. In the email world, the term “opt-in” refers to the process of explicitly choosing to join an email distribution list, or consenting to marketing emails. This should sound familiar to most email marketers, as getting consent before sending anything should be par for the course, and has been for quite a while. But the rigor with which we ask for consent is evolving, so let’s look at two different methods of obtaining consent; single opt-in and confirmed opt-in.

Single Opt-In

As the name implies, single opt-in requires a recipient to take a single action to grant permission to be added to a mailing list. This is typically achieved by entering an email address in a form, or clicking a button saying, “I’d like to receive email.” This may sound okay, and in some cases it is, but… Things can go wrong when using single opt-in.

Like what, you may ask. Well, someone might enter the wrong email address. In this scenario, the best thing that could happen is the email address turns out to be invalid. The occasional bounced address isn’t going to kill your reputation, but they can add up. It also means your recipient will not get the email they just signed up for, and that’s an L for the customer experience.

A troubling outcome is the erroneous address entered ends up belonging to someone else actively using the mailbox. In this scenario, the message you sent to the wrong person will likely generate a spam report. If your list hygiene isn’t up to snuff, future messages to that address will likely generate more spam reports and poor engagement. This is a reputation killer.

Here’s a worse scenario: Your new recipient enters a real email address which they used back in college, so the address is valid, but they haven’t logged into it in years. You might continue to send marketing messages to this address for months and never realize it has been long-since converted into a recycled spam trap. Every message you send to this address will be a mark against your sending reputation. Not good. Terrible, in fact.

Luckily, there is a tried and true solution that all but eliminates the possibility of any of these harmful scenarios. Enter confirmed opt-in (or “double opt-in”).

Confirmed Opt-In

Confirmed opt-in starts the same way as single opt-in. You must acquire consent from your potential recipient. However, after they share their email address, checked the box, or pressed the magic button, you immediately send them a confirmation email asking them to click a link to confirm their decision to sign up.

If the recipient fails to click the confirmation link, they should not be added to your email distribution list. Repeat: Do not add them to your sending list. Requiring the recipient to click a confirmation link does several things. It proves the address is real and the person who controls the address is the same person who provided it. Plus, you can rest assured they are legitimately interested in receiving email from you in the future.

There are pros and cons to each method of address collection. The benefits of single opt-in include having a more frictionless sign-up process and greater potential to collect more addresses. The downside is many of the addresses could be invalid and, for the reasons outlined above, open you up to list hygiene and reputation issues.

The benefits of confirmed opt-in include higher engagement rates, fewer unsavory addresses on your list, and should amount to significant decreases in reputation issues down the road. Plus, if you’re emailing the European Union, you won’t have to fret about providing evidence of your careful adherence to the GDPR! Yet, there are cons, like adding another step in your sign-up workflow, and potentially losing a good chunk of your would-be recipients because they fail to complete the additional confirmation step.

Truthfully, we think there are certain use cases for single opt-in. However, in today’s email ecosystem where spam and unwanted email is rampant, confirmed opt-in is almost always the right decision. The small hit you will take in your net address acquisition will be more than made up for in the increased engagement you’ll see from properly verified addresses. Confirmed opt-in will greatly reduce the number of messages you send to spam traps. This means fewer blacklistings and less time spent fighting deliverability issues. Kind of hard to beat that, isn’t it?

Author: Luke Martinez

Luke is a deliverability expert with a passion for getting email to the inbox. With more than four years at SendGrid prior to joining 250ok, his intimate understanding of the email ecosystem, email protocols, and marketing best practices allows him to provide data and insights that drive engagement and results from email programs both large and small.

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