curl --request POST \
  --url https://api.unibee.dev/merchant/email/send_email_via_api_credential \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "email": "<string>",
  "gatewayName": "<string>",
  "apiCredential": {
    "apiKey": "<string>",
    "apiSecret": "<string>",
    "authType": "<string>",
    "oauthToken": "<string>",
    "password": "<string>",
    "skipTLSVerify": true,
    "smtpHost": "<string>",
    "smtpPort": 123,
    "useTLS": true,
    "username": "<string>"
  },
  "content": "<string>",
  "language": "<string>",
  "subject": "<string>",
  "variables": {}
}
'

{
  "code": 123,
  "data": {},
  "merchantId": 123,
  "message": "<string>",
  "redirect": "<string>",
  "requestId": "<string>"
}