added 260907 version of worker toolkit

worker-toolkit-flaredown/repo/backend/app/mailers/application_mailer.rb

@@ -0,0 +1,9 @@
+class ApplicationMailer < ActionMailer::Base
+  default from: Rails.application.secrets.smtp_email_from
+
+  REGEXP = /\A\s*([-\p{L}\d+._]{1,64})@((?:[-\p{L}\d]+\.)+\p{L}{2,})\s*\z/i
+
+  def valid_email?(email)
+    email =~ REGEXP
+  end
+end