Single vs. Double Opt-In for SMS Subscriptions

Compares single and double opt-in for SMS and explains why Recart recommends double opt-in for most merchants.

Use this guide to choose the right opt-in method so you can build a clean, compliant SMS list while maximizing conversions.

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Overview

When setting up SMS marketing, one of the first choices you’ll make is how customers subscribe to your list: single opt-in or double opt-in. Both methods are compliant with TCPA and CTIA regulations, but they come with different risk levels. This guide explains the differences — and why we recommend double opt-in for most Recart merchants.

What Is Single Opt-In?

With single opt-in, customers are added to your SMS list immediately after they enter their phone number (e.g. via popup, checkout, or embedded form). No further confirmation is required.

Risks of Single Opt-In

Pros

• Fastest signup experience
• No additional user actions needed

Risks

• Anyone can enter any number — including one they don’t own
• You may end up sending SMS to people who never gave consent
• Can lead to compliance issues or legal risk, even if you’ve followed technical guidelines

What Is Double Opt-In?

Double opt-in adds a verification step to confirm that the person entering the phone number actually owns it. There are a few methods:

1. Two-Factor Authentication (2FA) – Recommended

   • A one-time passcode (OTP) is sent to the number
   • Customers verify directly on-site, without leaving the page
   • Cleanest and lowest-friction double opt-in option
2. Confirmation Text Message

   • Customer must reply “YES” or “CONFIRM” via SMS
   • Requires leaving the website to complete subscription
3. Deep Link (SMS App Redirect)

   • Customer is redirected to their Messages app to send a reply
   • Often causes drop-offs due to distractions

Comparison: Single vs. Double Opt-In

Factor	Single Opt-In	Double Opt-In (2FA)
Signup speed	Instant	+5–10 seconds
Conversion drop-off	None	2–8% typical
List quality	Lower—may include invalid numbers	Higher—verified numbers only
Compliance risk	Higher	Lower
Spam complaints	More likely	Less likely
Recommended for	Low-risk scenarios	Most merchants

Why We Recommend 2FA

Using a 2FA-based double opt-in ensures that:

• Your list contains only real, consented phone numbers
• You protect your brand from litigation or spam complaints
• You maintain high conversion rates (typically only 2–8% drop-off)

This method strikes the best balance between compliance, list quality, and user experience.

How to Choose Your Opt-In Type in Recart

To select your SMS opt-in type in Recart:

1. Go to your Recart dashboard
2. Click Opt-in Tools
3. Select Create New → Pop-up
4. At the top of the popup builder, choose your SMS opt-in type from the available options:

   • Double Opt-in (2FA)
   • One-Click Opt-in
   • Replying “YES” as Consent

smsoptintype

Once selected, click Continue to Editing to finish building your popup.

FAQs

Q: Is single opt-in illegal?

A: No — single opt-in is compliant with both TCPA and CTIA guidelines when implemented properly. However, it increases your exposure to risk and abuse.

Q: Will I lose conversions with double opt-in?

A: With 2FA-based verification, most merchants only see a 2–8% drop-off. For most, that’s a small price to pay for legal protection and higher list quality.

Best Practices

• Recommended: Use 2FA double opt-in for all popups to ensure list quality and compliance.
• Recommended: If you use single opt-in, monitor spam complaints and unsubscribe rates closely.
• Recommended: Clearly disclose what subscribers will receive before they opt in.
• Avoid: Using single opt-in for high-volume campaigns where invalid numbers could impact deliverability.

If you have any questions, do not hesitate to contact the Recart Support team. We'd be happy to help!