Understanding the Difference
Single Opt-In
User submits their email and is immediately added to your list. No confirmation required.
Double Opt-In (Confirmed Opt-In)
User submits their email, receives a confirmation email, and must click a link to confirm their subscription.
Single Opt-In Pros
- Larger list size (no confirmation friction)
- Simpler user experience
- Higher conversion rates
Single Opt-In Cons
- Higher invalid address rate
- More typos and fake emails
- Risk of spam complaints from people who didn't actually sign up
- No proof of consent
Double Opt-In Pros
- Verified, valid email addresses
- Higher engagement rates
- Documented proof of consent (GDPR compliance)
- Better list quality
- Lower spam complaint rate
Double Opt-In Cons
- Smaller list (10-20% don't confirm)
- Additional friction in signup
- Confirmation emails may hit spam
When to Use Each
Use Double Opt-In When: GDPR compliance required, quality over quantity matters, high-value email program
Use Single Opt-In When: Maximum list growth is priority, combined with real-time email validation, non-EU audience
Best of Both Worlds
Use single opt-in with real-time email validation through ValidateList. This catches invalid addresses at signup while maintaining a frictionless experience.