here you can find various ways of sending emails with .NET 2 / .Net 1 CDONTS / Persist’s AspEmail / VB / PHP etc
Use mod_rewrite and .htaccess file to block user agent libwww-perl. Open your .htaccess file and add rule as follows:
Not only do I block all accesses from libwww-perl, I also log what they were looking for which turns up an amazing amount of botnet hits on a daily basis just randomly hitting websites trying to find a way inside.
Please follow this link here to know how easy it is for a webserver to be compromised… Its a fantastic article, but in the end you will learn that its almost impossible to keep your server secure.