Disable or Suppress Transactional Receipt Emails

I want to be able to disable or suppress "Payment receipt" emails, especially for $0.00 trial signups. Currently, Creem sends a $0 receipt which confuses customers who also receive our branded welcome email. I'd like a merchant-level setting to disable transactional emails, a per-checkout `send_receipt: false` flag, or a way to suppress receipts specifically for $0 transactions while keeping them for real charges.