Speed up sign-in mail sending

app/controllers/sessions_controller.rb

@@ -36,16 +36,13 @@ class SessionsController < ApplicationController
   def email
     email = params[:email].downcase
 
-    # Use a transaction to ensure both user and email are created atomically
-    email_address = ActiveRecord::Base.transaction do
-      EmailAddress.find_by(email: email) || begin
-        user = User.create!
-        user.email_addresses.create!(email: email)
-      end
+    if Rails.env.production?
+      HandleEmailSigninJob.perform_later(email)
+    else
+      HandleEmailSigninJob.perform_now(email)
     end
 
-    LoopsMailer.sign_in_email(email_address).deliver_later
-    redirect_to root_path(sign_in_email: true)
+    redirect_to root_path(sign_in_email: true), notice: "Check your email for a sign-in link!"
   end
 
   def token

app/jobs/handle_email_signin_job.rb

@@ -0,0 +1,14 @@
+class HandleEmailSigninJob < ApplicationJob
+  queue_as :default
+
+  def perform(email)
+    email_address = ActiveRecord::Base.transaction do
+      EmailAddress.find_by(email: email) || begin
+        user = User.create!
+        user.email_addresses.create!(email: email)
+      end
+    end
+
+    LoopsMailer.sign_in_email(email_address).deliver_now
+  end
+end

app/mailers/loops_mailer.rb

@@ -1,14 +1,17 @@
 class LoopsMailer < ApplicationMailer
-  # Override the default mailer settings to use Loops.so SMTP
-  self.delivery_method = :smtp
-  self.smtp_settings = {
-    address: "smtp.loops.so",
-    port: 587,
-    user_name: "loops",
-    password: ENV["LOOPS_API_KEY"],
-    authentication: "plain",
-    enable_starttls: true
-  }
+  if Rails.env.development? && ENV["LOOPS_API_KEY"].nil?
+    self.delivery_method = :letter_opener
+  else
+    self.delivery_method = :smtp
+    self.smtp_settings = {
+      address: "smtp.loops.so",
+      port: 587,
+      user_name: "loops",
+      password: ENV["LOOPS_API_KEY"],
+      authentication: "plain",
+      enable_starttls: true
+    }
+  end
 
   def sign_in_email(email_address)
     @email = email_address.email