Email that is explicitly requested by the recipient.


The definition of opt-in email has been a matter of intense debate.

“single opt-in” vs. “double opt-in”

The term single opt-in simply means that actions were taken to sign up for the email in question. The term double opt-in means that the subscriber has actively confirmed their subscription, typically by responding to an automatically-generated message sent to the email address. Proponents of double opt-in may not actually use that term, as they feel any email labled “opt-in” must be verified.

see also: Email Marketing Tools

Related Terms

email marketing, permission marketing

view all terms in the Email Marketing glossary or all terms in the Digital Marketing glossary


Udemy: Email Marketing – learn email marketing with online courses.

view all options in Email Marketing courses or all types of Digital Marketing courses


ClickZ : Email Marketing


Opt-This, Opt-That: Putting Permission to Rest
Small Business Computing (October 18, 2002)

Six Ways to Build an Opt-In List (From Zero)
Small Business Computing (September 16, 2002)

Opt-In: More Than Permission to Send
Small Business Computing (September 13, 2002)

Whatever Happened to Opt-In?
ClickZ (January 25, 2001)

How Much Opt-In Is Enough?
ClickZ (September 4, 2000)

Speaking The Opt-In Language
ClickZ (November 22, 1999)