better consistency around email case sensitivity

lib/email.rb

@@ -1,8 +1,8 @@
 require 'mail'
+
 module Email
 
   def self.is_valid?(email)
-
     parser = Mail::RFC2822Parser.new
     parser.root = :addr_spec
     result = parser.parse(email)
@@ -12,4 +12,9 @@ module Email
     result && result.respond_to?(:domain) && result.domain.dot_atom_text.elements.size > 1
   end
 
+  def self.downcase(email)
+    return email unless Email.is_valid?(email)
+    email.gsub(/^(.+@{1})([^@]+)$/) { $1 + $2.downcase }
+  end
+
 end