auth_cram_md5

# File lib/net/smtp.rb, line 748
    def auth_cram_md5(user, secret)
      check_auth_args user, secret
      res = critical {
        res0 = get_response('AUTH CRAM-MD5')
        check_auth_continue res0
        crammed = cram_md5_response(secret, res0.cram_md5_challenge)
        get_response(base64_encode("#{user} #{crammed}"))
      }
      check_auth_response res
      res
    end