Opt-out
A list of email addresses with a working unsubscribe mechanism.
A list of email addresses, for example one used to send a newsletter, is called
opt-out if the owners of the addresses have not asked or agreed to be added to the list, but the
addresses can be removed from the list if requested.
While not illegal in some countries, the use of opt-out lists is considered bad practice and
email sent to such lists is generally believed to be spam. The preferred option is the use of
opt-in lists.
See also: opt-in.
