noun
opt-in
Refers to the act of choosing to receive something, such as emails or notifications, or the state of having chosen to participate. Common in marketing and IT contexts.
メールマガジンを受け取るには、オプトインが必要です。
Opt-in is required to receive the email newsletter.
このサービスはオプトイン方式を採用しています。
This service uses an opt-in method.