mail() using smtp in linux

i wanted to send a mail using smtp? isn't this possible from a linux-php ? i use a (linux-apache-php) for webservice and MS Exchg as mailserver. i do not have mailserver in the webserver. we are connected to the internet world through a proxy. this webserver is for inhouse applications only. so we do not have access to public networks. considering this it would be much easier if i could send mails through smtp. thanks ______________________________________________________ 123India.com - India's Premier Portal Get your Free Email Account at http://www.123india.com