You received this email because Zerodha refunded the ₹1 verification charge after linking your bank account using UPI.
When you link a bank account to your Zerodha account using UPI, Zerodha debits ₹1 from your bank account to verify that your bank details are accurate and belong to you. Zerodha automatically refunds the ₹1 to your bank account within 24 hours. Zerodha also sends you an email notification once the refund has been processed.