Single vs. Double Opt In: Which One is Better to Follow


Let’s say you gathered a lot of email addresses from people who sign-up on your website even to try out your solution once. And you then run a promotional email campaign on them. Later on, your email campaign meets a low response rate. In the end, all your effort becomes useless. On the other hand, implementing an ideal opt-in technique in your sign-up section can help you collect qualified leads.

Single and Double Opt In methods are the two most common opt-in processes widely used in sign-up or subscription. Opt-In strategies are effective in terms of generating leads. Opt-In forms can help a marketer collect a potential customer’s email addresses. Both the Single and Double Opt In methods offer unique benefits and drawbacks. We will soon discover it in detail.

What are the Single and Double Opt In?

Single Opt In (SOI)

Single Opt-In is a process where subscribers enter their email addresses in the sign-up form and will directly add the address to the company’s email list. In this process, the company didn’t take permission to collect the email address. Then the company may send any marketing email to these email lists. Single Opt-In is a single-step subscription process.

Double Opt In (DOI)

On the other hand, Double Opt-In is a two-step process. Here subscribers enter their email addresses in the sign-up form, and then a confirmation email or pop-up notification will send or appear to the subscribers. As a result, the subscribers can see that the company is asking for permission from them before collecting the email address. When subscribers click to confirm the subscription, they may only receive marketing emails from the company. Hence, the Double Opt-In process is known as “Confirmed opt-in.”

Legality scenario of Opt-In methods

You might wonder why the legal scenario needs to be observed here. Yes, it is pretty essential. Checking the legal factors is necessary when there is a way to get users’ information without their permission (which single opt-in does, apparently). 

According to the US CAN-SPAM Act, no complex rules exist regarding opt-in methods. This act allows the marketer’s direct marketing email messages or campaigns to be sent to anyone without permission. That indicates that an email marketer can use Single Opt-In methods to collect email addresses without legal issues. But they must include a clear Opt-Out (Unsubscribe) option in their marketing email message. When subscribers request to opt out, it must be processed within ten business days. However, according to US CAN-SPAM Act, opt-in methods have no complex rules. Nevertheless, US CAN-SPAM Act still discourages sending emails to unknown persons on average.

In contrast, according to the EU GDPR Act, the email sender must send marketing emails to those email recipients who gave permission (through an opt-in process). Moreover, some of the specific countries of the EU (e.g., Germany) have strictly made rules for email marketers to use the Double Opt-In methods. Therefore, it is clear that the EU GDPR Act strongly encourages email marketers to use opt-in forms (especially double opt-in).

Apart from the country’s laws and regulations, all leading ESP providers also strongly discourage sending emails without taking permission from the email receivers. For example, Amazon SES also highlighted the benefits of using the double opt-in methods in one of their blogs.

The pros and cons – Single and Double Opt In methods

You already got a hint that following the Double Opt-In method is more legitimate rather than a Single Opt-In process. Indeed the statement is true. But still, both opt-in ways have their different vital advantages and disadvantages. –

The advantages of Single Opt In –

  1. Easy process for subscribers: The Single Opt-In sign-up method minimizes the barriers to subscribing. Especially for those subscribers who want to subscribe to you for actual reasons. Single Opt-In is a simple process, as it creates only one step between you and your subscribers.
  2. Faster list growth: A Single Opt-In method confirms an easy sign-up process. Your email list growth rate will automatically increase. Whenever a webpage visitor completes the sign-up process, their email address is directly included in the company’s email list database. So, the process is swift and widely used for growing email lists quickly.
  3. Less chance of losing subscribers: There is less chance of losing the subscribers’ email addresses. Single Opt-In is a one-step process where the subscribers can sign-up for your service. They will automatically give you their email address while signing up if the marketer uses the Single Opt-In sign-up process. Thus all the email addresses will be stored in your database automatically. And the marketer won’t lose a single subscriber at all.

The disadvantages of Single Opt In –

  1. Low-quality leads: Lead generating through a Single Opt-In method is a poor quality strategy. Because through a Single Opt-In sign-up process, anyone can visit and sign-up quickly. Therefore, there is a solid chance to include lots of invalid or inactive email addresses in the email list. Single Opt-In users usually don’t cross-check the email address they get often. Consequently, the quality of the leads automatically gets down.
  2. Can affect the overall Email KPIs: If an email marketer follows the Single Opt-In lead generation techniques, it will affect the marketer’s Email marketing KPIs shortly. The quality of email addresses that will come through a Single Opt-In form may not be good. Therefore, it will affect the email sender’s reputation. Ultimately this will damage email delivery, click-through, open, click rates and so on. Moreover, the sender will face a high spam rate as well.
  3. Spambot becomes more harmful: Spambot is an automated program developed by a cybercriminal to collect email addresses from an active part of a website. It also creates fake email IDs and sign-ups to your website to steal all your subscriber’s email addresses from your email list database. An email spammer bot can smoothly bypass the Single Opt-In sign-up process and inject the marketer’s email list database. Undoubtedly the Single Opt-In method creates zero barriers in front of a cybercriminal.

The advantages of Double Opt In –

  1. Better email list quality: The most considerable advantage of using the Double Opt-In sign-up process is getting the most quality email address list. Because here, your subscribers will complete two steps before providing their email addresses to you. So, there is a higher likelihood that only potential users will subscribe to you and most importantly, they will do it “willingly.”
  2. Spambot becomes less harmful: Since there is no sign-up confirmation stage, the Single Opt-In approach encourages spambots, as was already explained earlier. On the other hand, the Double Opt-In can often prevent spambot attacks. The email spammer bot cannot complete the Double Opt-In method’s confirmation step (second step). Cybercriminals can deploy an email spammer bot on the email marketer’s webpage. But when a Double Opt-In feature exists, the email marketer efficiently filters the fake or spam sign-ups. A spambot can not act like a human, after all. However, cybercriminals are becoming more intelligent nowadays. Therefore not only the Double Opt-in is enough to stop a spambot. Along with Double Opt-In methods, a marketer should use “reCAPTCHA” to prevent email spammer bot attacks.
  3. Improved the overall Email KPIs: Ultimately, following the Double Opt-In methods will distinctly boost your email marketing KPIs. Though, it is true that it will take time to do so. But in the long run, the result will be muchly appreciable. The Double Opt-In method allows a marketer to collect valid and active emails. From those customers who will willingly give their addresses. As a result, the email delivery rate and all other email KPIs can reach a good percentage. Double Opt-In can remarkably reduce spam rate, which is a vital email marketing KPIs factor.

The disadvantages of Double Opt In –

  1. Slower list growth: Slow email list growth is one of the unavoidable facts of the Double Opt-In method. Indeed, it is not that big of a deal for a wise email marketer as they need an outcome in the long run. But it is a problematic fact for a new business or startup. Any new business or startup wants to grow their email list faster than usual.
  2. Longer process for subscribers: A Double Opt-In method is slightly longer than Single Opt-In. Because here, the subscriber cannot subscribe directly by filling up the sign-up form. After clicking for sign-up, a confirmation email is sent to the subscriber’s inbox, or a pop-up notification will appear in front of them. These confirmation steps take permission from the subscriber before adding their email address to an email list. Therefore Double Opt-In methods seem a bit long process.

Let’s wrap up both the Opt-Ins

Let’s make the decision more straightforward in the most simplistic way. Both opt-in methods are widely used for lead generation. Here are the critical factors for using the Simple and Double Opt-In forms. –

FactsSingle Opt-InDouble Opt-In
Sign-Up processSimple (with one step)Double (with two-step)
Sign-Up failure tendencyLowMedium
Faster email list growthPossibleNot Possible
Chance of getting inactive or invalid email addressesHighLow
Getting a quality Email listNot possibleHighly Possible
Personalized emailNot identically possiblePossible
Obtained subscriber’s engagement rateLowHigh
Chance of increasing Email deliverability rateLowHigh
Overall conversions rate after running a campaignLowMedium to High
Chance of Email spam complaintsHighLow
Spambot attacks chanceHighLow
Gaining subscriber’s trustNot possiblePossible
Marketer’s Brand reputationCan be affectedCan be boosted
Legality ScenarioQuestionableClear
Overall Email KPIs outcome (in the long run)Low to AverageGood to High

Now the decision is yours!

The single Opt-In method is popular among email marketers but is a weaker proof of the opt-in process. In comparison, the Double Opt-In way is a solid opt-in process. Let’s decide in one word on two factors between single and double opt-in: 

  • First, If you want to grow your email list fast, considering low email list quality and deliverability rate – You may use the Single Opt-In method. 
  • In contrast, if you want excellent subscriber engagement with a better deliverability and conversion rate in the long term – You may go for the Double Opt-In method.

However, the Double Opt-In method allows a marketer to send a confirmation message to the subscribers. When subscribers find that, the email sender takes permission from them before sending further marketing emails. Then the trust level goes up and creates a better relationship between them. Therefore, we MailBluster, along with all other popular Email Marketing tools, enormously appreciate the Double Opt-In method’s use in lead generation.


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