app/mailers/application_mailer.rb

@@ -1,4 +1,5 @@
 class ApplicationMailer < ActionMailer::Base
+  default Rails.application.config.action_mailer.default_options
   layout 'mailer'
 
   private
@@ -19,7 +20,7 @@ class ApplicationMailer < ActionMailer::Base
     end
 
     def from_address
-      ENV.fetch('SMTP_FROM_ADDRESS', 'accounts@localhost')
+      self.class.default[:from]
     end
 
     def from_domain

config/environments/development.rb

@@ -57,16 +57,22 @@ Rails.application.configure do
   # routes, locales, etc. This feature depends on the listen gem.
   config.file_watcher = ActiveSupport::EventedFileUpdateChecker
 
-  config.action_mailer.default_options = {
-    from: "accounts@localhost"
-  }
-
   # Don't actually send emails, cache them for viewing via letter opener
   config.action_mailer.delivery_method = :letter_opener
+
   # Don't care if the mailer can't send
   config.action_mailer.raise_delivery_errors = true
+
   # Base URL to be used by email template link helpers
-  config.action_mailer.default_url_options = { host: "localhost:3000", protocol: "http" }
+  config.action_mailer.default_url_options = {
+    host: "localhost:3000",
+    protocol: "http"
+  }
+
+  config.action_mailer.default_options = {
+    from: "accounts@localhost",
+    message_id: -> { "<#{Mail.random_tag}@localhost>" },
+  }
 
   # Allow requests from any IP
   config.web_console.permissions = '0.0.0.0/0'

config/environments/production.rb

@@ -63,7 +63,7 @@ Rails.application.configure do
   outgoing_email_domain  = Mail::Address.new(outgoing_email_address).domain
 
   config.action_mailer.default_url_options = {
-    host: ENV['AKKOUNTS_DOMAIN'],
+    host: ENV.fetch('AKKOUNTS_DOMAIN'),
     protocol: "https",
   }
 

config/environments/test.rb

@@ -46,8 +46,12 @@ Rails.application.configure do
 
   config.action_mailer.default_url_options = {
     host: "accounts.kosmos.org",
-    protocol: "https",
-    from: "accounts@kosmos.org"
+    protocol: "https"
+  }
+
+  config.action_mailer.default_options = {
+    from: "accounts@kosmos.org",
+    message_id: -> { "<#{Mail.random_tag}@kosmos.org>" },
   }
 
   config.active_job.queue_adapter = :test