Glossary - Double Opt-In

Wording used usually by spammers to imply the recipient has "opted-in twice". The first time, says the spammer, was when the address was obtained and "opted-in" by the spammer without the recipient's consent, the second time was when the recipient failed to opt-out after receiving spam. Reference: http://www.spamhaus.org/mailinglists.html The correct method for securing a mailing list is by the usage of Confirmed Opt-In also called Verified Opt-In.