opt-in

基本解释

This means more retailers are sending at least one email in the crucial first 30 days after opt-in.
这就意味着越来越多的零售商在客户选择性加入后的至关重要的30天内至少会发出一封邮件。
In this application, the system first sends out an opt-in request notification to users it finds, asking for their communication data upload.
在此应用程序中，系统首先向找到的用户发送 opt-in 请求通知，请他们上传通讯数据。
Latitude is a similar opt-in service to My Location, except it allows you to share locations between friends based on your mobile phone or desktop location.
是一个与我的位置相似的服务，只不过它是允许你在你的朋友间分享你基于移动电话或者桌面电脑的位置。

Hopefully, if you opt-in for this tablet, you can live with that permanent application load.
ENGADGET: Samsung Galaxy Tab 2 7.0 review
"Opt-in is really the most burdensome privacy restriction that we implement in the U.S., " Zanneis says.
FORBES
After a few weeks, YesMail agreed to the stricter double opt-in rule and dropped its suit.
FORBES: Spam Warfare