Double opt-in, abbreviated DOI, is a lead-qualification model in which a user submits their contact details and then must confirm them by clicking a link in an email or entering a code from an SMS before the conversion counts.
Definition
Double opt-in, abbreviated DOI, is a lead-qualification model in which a user submits their contact details and then must confirm them by clicking a link in an email or entering a code from an SMS before the conversion counts. The confirmation step filters out mistyped addresses, disposable inboxes, bot submissions and users who hesitate, so the advertiser receives a verified, reachable contact rather than an unvalidated form fill.
DOI offers pay more per lead than single opt-in offers for the same product, because the advertiser is buying a contact it can actually use — an email that receives mail, a phone that receives SMS, a person who took a deliberate second action. The cost of that quality is a lower confirmed rate: every user who submits but does not confirm is a lost payout, so the confirmation experience — clear instructions, fast delivery, a visible resend option, a confirmation page that reassures — is where a DOI affiliate wins or loses money.
In context
DOI is standard for verticals where a reachable contact is the product being sold: sweepstakes, dating, newsletters, and lead generation for finance and insurance. It is also common in compliance-sensitive GEOs and channels where explicit, provable consent to be contacted is a legal requirement, since the confirmation click is a record of that consent.
In iGaming proper, registration flows are usually governed by the operator's platform and licence rather than a DOI mechanic, but DOI patterns appear in adjacent lead-gen funnels that feed operators.
An affiliate running DOI monitors two rates: the submit rate on the landing page and the submit-to-confirm rate. A high submit rate with a poor confirm rate points to a broken or slow email step, an unclear instruction, or traffic that is curious but not committed.
Optimising DOI is largely about compressing the time and friction between submit and confirm — instant email delivery, a one-tap confirmation link, an SMS fallback — because every minute of delay and every extra step sheds confirmations and payout.
Worked example
A DOI sweepstakes offer pays $2.20 per confirmed lead. The affiliate's landing page converts 30% of visits to a submit, but only 62% of submits confirm, mostly because the confirmation email arrives slowly.
Adding an instant SMS confirmation option lifts the confirm rate to 78%, raising effective revenue per visit by a quarter with no change in traffic.
Related terms
Frequently asked questions
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