The Difference Between Opt-In and Double Opt-In

You've certainly heard email marketers use the term "opt-in": messages are sent only upon the recipient's permission.

Others talk about "double opt-in" (or "confirmed opt-in") as if it was a completely different matter. But is it?

The Difference Between Opt-In and Double Opt-In

• Email addresses on a (single) opt-in list are not confirmed. Anybody can submit anybody's address to the list, and it will be there until it is unsubscribed.
• On a double opt-in list, all email address must be confirmed before they are added. A request for confirmation is sent to the submitted address and the address owner must take some action to confirm that
  • she is the owner of the email address,
  • the address is working and
  • she indeed wants to subscribe.
  Most often, the confirmation action is as simple as replying to the confirmation request or clicking on a link.