Billing API

Upgrade to the paid plan via Stripe checkout.

POST /v1/billing/upgrade

POST/v1/billing/upgrade

Generate a Stripe checkout URL to upgrade from the free plan to paid. Requires full-access key. No request body needed.

response — 201 Created

{
  "checkout_url": "https://checkout.stripe.com/c/pay_...",
  "expires_at": 1741651200,
  "message": "Complete payment at the checkout URL"
}

After payment, your account is upgraded automatically. The paid plan costs $5/mailbox/month with a 3-mailbox minimum ($15/month).