The affiliate glossary ↗AFFDude / Field notes
DOI
In plain English
What does DOI mean?
Double opt-in: the lead only counts after the user confirms by email (or SMS), so it pays more than SOI.
DOI cuts fake leads at the source. The confirmation step loses a share of users, so conversion rate drops and payout rises. Which is better depends on your traffic: high-intent traffic does fine on DOI, cold pop traffic usually does better on SOI.