curl --request GET \
  --url https://test.deribit.com/api/v2/private/set_email_language \
  --header 'Content-Type: application/json' \
  --data '
{
  "jsonrpc": "2.0",
  "id": 3269,
  "method": "private/set_email_language",
  "params": {
    "language": "en"
  }
}
'

{
  "jsonrpc": "2.0",
  "id": 1569,
  "result": "ok"
}