Legit question this time (mail and PHP)

[Paul Spicer]

I'm trying to get PHP's mail() command to work, but alas, no luck so far.
All solutions I've found require me to set my box up as an SMTP server
(using postfix). We already have one mail server on this network! How can I
convince PHP to send email WITHOUT having to add 'mail server' to this box's
job requirements?