code: def regex(self):
          
  
          qtext = '[^\\x0d\\x22\\x5c\\x80-\\xff]'
          dtext = '[^\\x0d\\x5b-\\x5d\\x80-\\xff]'
  
          atom = '[^\\x00-\\x20\\x22\\x28\\x29\\x2c\\x2e\\x3a-\\x3c\\x3e\\x40'
          atom += '\\x5b-\\x5d\\x7f-\\xff]+'
  
          quoted_pair = '\\x5c[\\x00-\\x7f]'
          domain_literal = "\\x5b(?:%s|%s)*\\x5d" % (dtext, quoted_pair)
          quoted_string = "\\x22(?:%s|%s)*\\x22" % (qtext, quoted_pair)
          domain_ref = atom
          sub_domain = "(?:%s|%s)" % (domain_ref, domain_literal)
          word = "(?:%s|%s)" % (atom, quoted_string)
          domain = "%s(?:\\x2e%s)*" % (sub_domain, sub_domain)
          local_part = "%s(?:\\x2e%s)*" % (word, word)
          addr_spec = "%s\\x40%s" % (local_part, domain)
  
          email_address = re.compile('\A%s\Z' % addr_spec)
          return email_address
docs: RFC822 Email Address Regex
          Originally written by Cal Henderson
          c.f. http://iamcal.com/publish/articles/php/parsing_email/
          Translated to Python by Tim Fletcher with changes suggested by Dan Kubb
          http://tfletcher.com/lib/rfc822.py
          Licensed under a Creative Commons Attribution-ShareAlike 2.5 License
          http://creativecommons.org/licenses/by-sa/2.5/
          :return: