Before diving into this topic, I want to explain the “opt-in” terminology in email marketing. Opt-in means the new subscription of an email address. There are two subscription methods:

  • Single opt-in subscription
  • Double opt-in subscription

Let’s look closely at both.

Single Opt-in Subscription

This method involves a one-click subscription. Your website visitor simply enters their email address on your subscription form. Afterwards their subscription is activated immediately.


  • Instant subscription
  • Higher converts. Since one action is all that’s needed to subscribe, you gain more subscribers


  • Anyone can use any email address to subscribe, which can cause higher bounces and spam complaints
  • Emails with typos can subscribe. This causes hard bounces, further resulting in bad delivery performance
  • Your list might have several invalid email addresses and false subscriptions, which can cause low email open rates and high unsubscribe rates

Double opt-in subscription

This is a two-layer subscription process. First, visitors enter their email addresses on your subscription form. Once the form is submitted, the system sends a confirmation email to the entered email address.

Next visitors open the received confirmation email and click the subscription’s confirmation link. Once this link is clicked, the subscription gets activated.

Unless this link is clicked, the subscription remains “pending”. It never gets activated.


  • Your list will contain 100% active, engaged email addresses
  • Your emails will have higher open rates because your recipients will be highly engaged subscribers
  • Less hard bounces (invalid email address), spam complaints and unsubscribe rates, which means higher delivery performance


  • This process can be complicated. Because some visitors are frightened of the “unknown”, they simply abandon the process before confirming their subscriptions
  • Less conversion rates

Which Subscription Method Should You Choose?

Each subscription method has different advantages as well as disadvantages. Therefore, we can not suggest one over another.

However, using the right opt-in method will definitely help you achieve higher email open rates, which will result in higher conversion rates.

For generic lists such as your website mail list subscription form or a “stay updated” mail list, using the double opt-in confirmation may be more suitable. These subscription forms usually get higher impressions and subscription rates.

Therefore, your focus point on these subscription forms should be acquiring highly active, engaged subscriptions. And this is only possible with the double opt-in confirmation.

On the other hand, the single opt-in subscription method can produce better results for “event specific” subscription forms such as the following:

  • Discount notification list
  • Product trial list
  • Subscribe and get access list
  • Subscribe and learn more list

Single opt-in subscription works with these because the visitors are already interested and ready to engage in subscribing. All they have to do is just enter their email address, click the subscribe button and that’s it.

Thus, your main objective in this situation is to get their email addresses as quickly as possible.

How do I Change the Subscription Method of my Lists in Sendloop?

You can choose the subscription method for each list you have in your Sendloop account. To learn how to set it, read our article How to Change the Subscription Method of a Subscriber List