Sandra most likely, signed up for an opt-in program.
It usually refers to email communication.
It is so because opt-in process is used to describe when a positive action is required in order to accede a user to a newsletter list. The term opt-in means something you choose to do or going to be involved in.
Opt-in is given by the users as a form of consent, noticing the interest in a product or service by allowing the third-party to interact with them and share the further details with them.
It is also known as permission marketing and could be single or double opt-in.
To learn more about opt-in here
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