Sending mail from a Unix

I'm running a couple of web scripts in a Unix system with Apache. I need to send an email message with some info but I have to do it using a SMTP running in another server on my network. How can I do this? I've tried setting the SMTP parameter in the php.ini file, but it'd only work if I'm running WinNT. Note: I can't send it via sendmail command line (local). Any ideas? Thanks, Jaime