Add punycode email support

lib/email_address_converter.rb

@@ -0,0 +1,33 @@
+module EmailAddressConverter
+  module_function
+
+  def punycode_to_unicode(email)
+    return email if domain(email) == 'not_found'
+
+    local = local(email)
+    domain = SimpleIDN.to_unicode(domain(email))
+    "#{local}@#{domain}"&.downcase
+  end
+
+  def unicode_to_punycode(email)
+    return email if domain(email) == 'not_found'
+
+    local = local(email)
+    domain = SimpleIDN.to_ascii(domain(email))
+    "#{local}@#{domain}"&.downcase
+  end
+
+  private
+
+  def domain(email)
+    Mail::Address.new(email).domain&.downcase || 'not_found'
+  rescue Mail::Field::IncompleteParseError
+    'not_found'
+  end
+
+  def local(email)
+    Mail::Address.new(email).local&.downcase || email
+  rescue Mail::Field::IncompleteParseError
+    email
+  end
+end