Phoenix: Pow not sending confirmation e-mail on laptop

I’m using Pow for user authentication in my app. Up until recently I’ve been developing on an iMac without any issues (i.e. I was able to create users, receive the confirmation email, reset their passwords, etc.) but I recently decided to get a new laptop (a MacBook Pro) to develop on. I was able to setup my development environment without any issues, but when I went to create a new user and confirm the new account the confirmation email didn’t get sent. I see this message in the logs:

[warn] Mailer backend failed with: {:option, :server_only, :honor_cipher_order}

Here’s the custom mailer backend as well:

defmodule TrumpetWeb.PowMailer do
  use Pow.Phoenix.Mailer
  use Swoosh.Mailer, otp_app: :trumpet_web

  import Swoosh.Email

  require Logger

  def cast(%{user: user, subject: subject, text: text, html: html, assigns: _assigns}) do
    |> to({,})
    |> from({"Dev - Trumpet", ""})
    |> subject(subject)
    |> html_body(html)
    |> text_body(text)

  def process(email) do
    |> deliver()
    |> log_warnings()

  defp log_warnings({:error, reason}) do
    Logger.warn("Mailer backend failed with: #{inspect(reason)}") # This is the log message I'm getting. `reason` doesn't provide much info.

  defp log_warnings({:ok, response}), do: {:ok, response}

I’ve search for the cause of that reason but haven’t been able to find anything useful. I also added inspect to various places in the process function and can confirm the email is generated and the confirmation link works (i.e. I can click the confirmation link from the logs and confirm the user without any issues). What’s also weird is that if I push the changes from my laptop to GitHub, pull them down on to my iMac, and build and run the app then the code works(?!).

Any ideas on what could be going on? I’m using an umbrella app, so here’s the web component’s deps:

  defp deps do
      {:phoenix, "~> 1.4.9"},
      {:phoenix_pubsub, "~> 1.1"},
      {:phoenix_html, "~> 2.13.3"},
      {:phoenix_ecto, "~> 4.0.0"},
      {:phoenix_live_reload, "~> 1.2", only: :dev},
      {:gettext, "~> 0.11"},
      {:jason, "~> 1.0"},
      {:plug_cowboy, "~> 2.0"},
      {:plug, "~> 1.8.3"},
      {:stripity_stripe, "~> 2.4.0"},
      {:trumpet, in_umbrella: true},
      {:swoosh, "~> 0.23.3"},
      {:gen_smtp, "~> 0.13"},
      {:phoenix_swoosh, "~> 0.2.0"},
      {:pow, "~> 1.0.11"}
# config.exs:
config :trumpet_web, :pow,
       user: Trumpet.User,
       repo: Trumpet.Repo,
       mailer_backend: TrumpetWeb.PowMailer
# dev.exs:
config :trumpet_web,
       adapter: Swoosh.Adapters.Sendgrid,
       api_key: "SG.X.X"

Please let me know if this isn’t the right place to ask this question. It seems like it might be an issue specific to the computers I’m using, but just want some other opinions.

It’s :hackney (in Swoosh deps) that causes the error:

The solution is to update :hackney to 1.15.2.

Thanks, that was it. I appreciate the fast response!