Double opt-in (also called confirmed opt-in) requires subscribers to verify their email address by clicking a link in a confirmation email before they are added to your list. This eliminates typos, bots, and low-intent sign-ups, resulting in a cleaner list, better engagement rates, and stronger regulatory compliance.
What It Does to Your List
Expect a 20–40% reduction in new subscriber volume when switching to double opt-in. The contacts you keep are significantly more engaged — they confirmed intent twice. Open rates typically improve 10–20% on double-opted-in lists compared to single opt-in lists of equivalent size.
Steps
Go to the form settings for your opt-in form
Navigate to Sites → Forms or find the form in your funnel step settings.
Look for the Double Opt-In or Email Verification setting
Toggle it on.
Customize the confirmation email
Edit the confirmation email that subscribers receive. Make it clear what they are confirming and what they will receive.
Set the redirect for confirmed contacts
Where do contacts land after clicking the confirmation link?
Test the full flow
Submit the form with a test email. Confirm the confirmation email arrives. Click the link. Confirm the contact is created and the redirect fires.
When to Use Double Opt-In
Always use for: audiences in the EU or UK (GDPR requirement), any list where you plan to send commercial offers, new lead magnets or freebie campaigns where motivation to sign up may be low-intent.
Consider single opt-in for: a paying customer who is giving you their email as part of a purchase — the purchase itself is evidence of intent.
- Writing a generic confirmation email — be specific about what the subscriber is confirming.
- Not testing the full double opt-in flow after configuring it.
- Using double opt-in for a purchase checkout form — buyers have already confirmed intent with their payment.
- Expecting the same volume from double opt-in as single opt-in — the reduction is the point.
Next steps
- How to Clean Your Email List — double opt-in reduces the cleaning needed over time
- Understanding Email Deliverability Scores — see the deliverability impact of double opt-in over time
Still stuck?
- Search the MONDAi Help Center
- Email support@mondai.io with a Loom video
- Ask inside the ArchiTech Channel
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