Fix #1624 - Send e-mail notifications to admins about new reports (#3949)

app/mailers/admin_mailer.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+class AdminMailer < ApplicationMailer
+  def new_report(recipient, report)
+    @report   = report
+    @me       = recipient
+    @instance = Rails.configuration.x.local_domain
+
+    locale_for_account(@me) do
+      mail to: @me.user_email, subject: I18n.t('admin_mailer.new_report.subject', instance: @instance, id: @report.id)
+    end
+  end
+end