What do you mean by unsubscribing back to R?

It means to unsubscribe from a business or service.

When the user receives a short message or email with the subscribed content, the reply letter "R" means canceling the subscription. In some cases, replying to other specific keywords can also achieve the purpose of unsubscribing. Unsubscribe back to "R" is usually used for commercial marketing, advertising promotion and membership service.

After unsubscribing, the SMS service provider will mark this number as a blacklist, and will not send similar SMS to this number in the future, so as to avoid complaints from the number owner.