How to use Smart Opt-in to collect SMS consent in sign-up forms

You will learn

Learn how to enable Smart Opt-in in a sign-up form to easily collect and verify SMS consent from site visitors. When a shopper inputs their phone number into a form with Smart Opt-in enabled, they’ll receive a one-time code that they can click to autofill on iOS and Android browsers to confirm their consent for SMS marketing.

SMS sign-up forms with Smart Opt-in reduce the friction of shoppers needing to take action in their messages app, and minimize distractions since shoppers can opt in without needing to leave your site. They can also help you avoid list bombing when using a branded sender ID. 

Before you begin

Note that if you downgrade to a free SMS plan after creating 1 or more Smart Opt-in sign-up forms, these forms will no longer work. You will either need to republish the forms without the Smart Opt-in step, or resume your paid SMS plan so that they function properly. 

How Smart Opt-in works

The process for collecting SMS consent in a sign-up form through Smart Opt-in works as follows:

1. A site visitor inputs their phone number in a form with Smart Opt-in configured.
2. The site visitor receives a text at that phone number with a one-time code (e.g., 123456).
   

   The one-time code will not send from your brand’s regular sending number;  it will send from a short code managed by Klaviyo, so this message will not be on the same thread as your regular, promotional messages.

3. The site visitor sees an additional form step asking for a one-time authentication code.
4. Based on their device type, the site visitor enters the code and submits the form to confirm their opt-in status.
• If the visitor is viewing the form on a mobile device, they can click to autofill the one-time code on any iOS or Android browser.
• If the visitor is viewing the form on desktop, they must manually copy the code from their SMS messages into the form.

To learn about how Smart Opt-in compares to other SMS consent collection methods (e.g., tap-to-text), check out our SMS opt-in methods reference.

Configure Smart Opt-in in a sign-up form

To begin, navigate to Sign-up forms in Klaviyo’s left-hand navigation. From here, you can either:

• Customize a pre-built template that has Smart Opt-in already configured
• Configure Smart Opt-in on one of your existing forms

Customize a template with Smart Opt-in pre-configured

1. In the top right corner, select Create form. 
2. Open the All Categories dropdown, then check the box for Smart Opt-in to filter the form library.
   
3. Choose a pre-built template from the filtered options. These options have Smart Opt-in already configured by default. 
4. On the preview modal:
• Name your form
• Choose the list that new subscribers will submit to
• Select whether to include a form teaser
  
5. Select Create form to enter the form editor.
6. Select Targeting and behavior, then click Targeting.
7. Under Location, click Show to visitors in certain locations, then select the countries where you have an active sending number from the dropdown (e.g., United States, United Kingdom, etc.). Targeting your form to these countries ensures that only site visitors who can receive the one-time code will see it.
   
8. Customize the content, design, and behavior of your form to fit your brand and goals. See getting started with sign-up forms for more guidance on editing your form.
   

   Be sure to customize each step of your form, including the One-time code step and Success step.

   

All Smart Opt-in templates have an SMS Opt-in step followed by a One-time code step. All steps include a submit button, and the One-time code step additionally includes a Resend Code button. Klaviyo will pre-configure the buttons on each of the form’s steps with the appropriate action settings, so you do not need to adjust them manually. Note that some pre-built Smart Opt-in templates may also include an Email Opt-in step before or on the same step as the SMS Opt-in. 

When you’re finished customizing your sign-up form, click Publish. Then, see the SMS messaging details for Smart Opt-in section for SMS billing information.

Configure Smart Opt-in on an existing form

You can configure Smart Opt-in on an existing, email-only form, or alternatively, you can change an existing SMS opt-in form to use Smart Opt-in. The following sections will outline each option.

Add Smart Opt-in to an existing email-only form 

If you have an existing form that collects email consent only, add an SMS step and configure Smart Opt-in:

1. Next to the form you’d like to add Smart Opt-in to, select the 3 dots > Edit. 
2. Click (+) Step in the menu bar to add a step.
   
3. Select SMS Opt-in > Next.
   
4. Choose the list that new SMS subscribers will join, then select Smart Opt-in.
5. Click Add step.
   
6. Customize the design and content on the newly added SMS Opt-in step and the One-time code step to match the rest of the form.
7. Select Targeting and behavior, then click Targeting.
8. Under Location, click Show to visitors in certain locations, then select the countries where you have an active sending number from the dropdown (e.g., United States, United Kingdom, etc.). Targeting your form to these countries ensures that only site visitors who can receive the one-time code will see it.
   
9. Verify that you do not have any active alerts in the Form alerts tab in the lower left corner of the editor.
10. Click Publish changes. 
11. See the SMS messaging details for Smart Opt-in section for more information. 

Change an existing SMS form to use Smart Opt-in

If you have an existing SMS sign-up form, change the opt-in method to use Smart Opt-in:

1. Click on the phone number input block in the preview. 
2. Under SMS opt-in method in the left-hand menu, select Enable.
   
3. Click Smart Opt-in > Add step.
   
4. Customize the design and content of the One-time code step and Success steps to match the rest of the form.
   
5. Select the Targeting and behaviors tab, then click Targeting.
6. Under Location, click Show to visitors in certain locations, then select the countries where you have an active sending number from the dropdown (e.g., United States, United Kingdom, etc.). Targeting your form to these countries ensures that only site visitors who can receive the one-time code will see it.
   
7. Verify that you do not have any active alerts in the Form alerts tab. 
8. Click Publish changes.
9. See SMS messaging details for Smart Opt-in section for more information on messaging with Smart Opt-in. 

SMS messaging details for Smart Opt-in

Once published, site visitors who submit their phone number on the SMS Opt-in step will receive an SMS message containing a one-time code. The message will read as follows:

“Your {SMS Organizational Prefix} verification code is: 123456”

Klaviyo will automatically translate this message to the appropriate language based on the recipient’s country code. This message will not count against your brand’s SMS credits, even if a shopper requests multiple authentication codes. Similarly, Klaviyo will not record a Received SMS event on the recipient’s profile for this message.

The respective code will auto-detect on iOS and Android browsers, so site visitors can easily click to auto-fill the code in the form to verify their opt-in status without ever needing to leave your site. If a shopper is browsing on a desktop, they’ll need to manually copy the code from their mobile device.

Once a site visitor adds the code and submits the One-time code step, they will see the form’s Success step and their Klaviyo profile will reflect a Subscribed consent status for SMS marketing. Additionally, a Subscribed to SMS Marketing event will log on the subscriber's Klaviyo profile with the date and time of their opt in.

If a site visitor inputs an incorrect code into the form, they’ll see an error alerting them of an invalid code, and the option to re-enter the code or request a new one. 

See getting started with form analytics for guidance on tracking performance metrics for your form, including submit rates per step so you can see where potential subscribers are abandoning the opt-in experience within your form. 

Troubleshooting Smart Opt-in

Delivery of messages containing the one-time code is dependent upon the end carrier, so delays and message failures can still occur in the case of an outage. 

As a best practice for protecting against these instances, consider adding an SMS subscribe link in a smaller font at the bottom of your One-time code step in case someone has difficulty with the one-time code. Alternatively, if you have two-way messaging capabilities, you can also add additional text to your form with instructions for sending your subscribe keyword to your sending number (e.g., “Having trouble with the code? Instead, text JOIN to ### to subscribe.”).

If you include a backup opt-in method on the One-time code step, ensure that the required disclosures are included for that method (e.g., subscribe link, tap-to-text, etc.).

Additional resources

How to A/B test Smart Opt-in versus other SMS opt-in methods

Understanding SMS opt-in methods

Basics: SMS compliance