Async tasks in a process failsafe

sender_application.ex

defmodule Sender.Application do
  # See https://hexdocs.pm/elixir/Application.html
  # for more information on OTP Applications
  @moduledoc false

  use Application

  @impl true
  def start(_type, _args) do
    children = [
      # Starts a worker by calling: Sender.Worker.start_link(arg)
      # {Sender.Worker, arg}
      {Task.Supervisor, name: Sender.EmailTaskSupervisor}
    ]

    # See https://hexdocs.pm/elixir/Supervisor.html
    # for other strategies and supported options
    opts = [strategy: :one_for_one, name: Sender.Supervisor]
    Supervisor.start_link(children, opts)
  end
end

sender_lib_sender.ex

defmodule Sender do
  @moduledoc """
  Documentation for `Sender`.
  """

  @doc """
  Hello world.

  ## Examples

      iex> Sender.hello()
      :world

  """
  def hello do
    :world
  end

  def send_email("konnichiwa@world.com" = email),
    do: raise("Oops, couldn't send email to #{email}!")

  def send_email(email) do
    Process.sleep(3000)
    IO.inspect("Email to #{email} sent")
    {:ok, "email sent"}
  end

  def notify_all(emails) do
    Sender.EmailTaskSupervisor
    |> Task.Supervisor.async_stream_nolink(emails, &send_email/1)
    |> Enum.to_list()
  end
end