Originally Posted by 1080p Content

One person tried to send me cash using his prepaid debit card, but seems it won't accept such cards.

In theory it works as this:

1. Person A sends the email TO you and CC square.com with the amount in the subject.
   
2. Then square sends an email to person A to link a debit card to his email (if first time use), and another email to person B telling that person A is sending you $x amount, and that after confirmation you will receive a link to deposit it.
   
3. When person A confirms the payment, person B receives and email with a link to deposit the money to his debit card or bank account (if first time use, otherways is auto).