Your robots.txt should be blocking these urls:
http://www.example.com/tools/email.php
http://www.example.com/tools/email.php?aid=100 It will allow Google to access a url like this:
http://www.example.com/red/tools/email.php
Also please remember that rel="nofollow" was not intended to restrict robot access (even though it is called nofollow). Its purpose is to identify untrusted links to Google.
