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What Is Opt-In?
Email Marketing
Updated 18 September 2026
Quick Answer
An opt-in is when someone explicitly gives permission to receive communication from a business — typically by submitting their email address — the required, legitimate basis for adding them to a marketing list.
Opt-In vs. Cold Email — What's the Difference?
| Opt-In | Cold Email | |
|---|---|---|
| Consent basis | Explicit permission given by the recipient | No prior permission or relationship exists |
Why It Matters
- It's often a legal requirement (under GDPR and similar regulations) for sending marketing communications, not just good practice.
- An opted-in list also tends to engage far better than one built without genuine consent, since recipients actually want to hear from you.
How It Works
- A visitor is offered a way to sign up — a form, a lead magnet, a checkout option.
- They explicitly submit their details, giving permission for future contact.
- This opt-in status is recorded, forming the legitimate basis for future marketing communication.
Key Takeaways
- An opt-in is explicit permission to receive marketing communication.
- It's typically a legal requirement, not just best practice.
- An opted-in list engages better than one built without genuine consent.
Frequently Asked Questions
What's the difference between single and double opt-in?
Single opt-in adds someone immediately after they submit a form; double opt-in requires an additional confirmation click via email before they're fully subscribed.
Is opt-in legally required for email marketing?
In most regions, yes — regulations like GDPR require explicit consent before sending marketing communications.
Does double opt-in reduce list size?
It typically does, but the resulting list is more engaged and legally safer, since every contact has explicitly confirmed consent.