Add Message-ID header to outgoing emails (#16076)

* Add Message-ID header to outgoing emails

* Use email domain name from SMTP_FROM_ADDRESS, fallback on WEB_DOMAIN on failure

* Use notifications@localhost as fallback for SMTP_FROM_ADDRESS, do not catch parse errors

config/environments/production.rb

@@ -90,9 +90,12 @@ Rails.application.configure do
   config.action_mailer.perform_caching = false
 
   # E-mails
+  outgoing_email_address = ENV.fetch('SMTP_FROM_ADDRESS', 'notifications@localhost')
+  outgoing_mail_domain   = Mail::Address.new(outgoing_email_address).domain
   config.action_mailer.default_options = {
-    from: ENV.fetch('SMTP_FROM_ADDRESS', 'notifications@localhost'),
+    from: outgoing_email_address,
-    reply_to: ENV['SMTP_REPLY_TO']
+    reply_to: ENV['SMTP_REPLY_TO'],
+    'Message-ID': -> { "<#{Mail.random_tag}@#{outgoing_mail_domain}>" },
   }
 
   config.action_mailer.smtp_settings = {