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Double opt-in occurs when

a user has elected to receive an e-mail newsletter[] or stand-alone commercial message. A confirmation e-mail is then sent to the user to which he/she must reply (either by replying to the message or clicking on a URL contained within) before the list owner may add them to their list.[1]


Double opt-in is a

process that requires consumers to take two separate steps to authorize a third-party charge, one of which is intended to confirm that the consumer is in physical possession of a phone tied to the account that will be charged.[2]


"Common forms of double opt-in include:

  1. Mobile phone opt-in — a consumer sends a text message with a keyword to a short code, receives a confirmation text, and then sends a second text message to confirm the transaction;
  2. Web opt-in — a consumer first enters his or her number on a website, then receives a text with a PIN, which the consumers enters back into the website;
  3. WAP (wireless access protocol) — a consumer responds to an offer on his or her phone ([[display]ed through the mobile web), and clicks on a confirmation button on the phone two separate times; and
  4. IVR (interactive voice response) — a consumer opts-in over the phone through a toll-free number and confirms the transaction twice."[3]


  1. Council for Responsible E-mail, E-mail Delivery Best Practices for Marketers and List Owners 3 (Oct. 2005) (full-text).
  2. Mobile Cramming: A Federal Trade Commission Staff Report, at 27-28.
  3. Id. at 28.