You'll have to setup Postfix a bit before using it, but there isn't much to do.
Open the file /etc/postfix/main.cf
You can type in that path in Textedit or use pico or some other command line text editor.
First you'll want to setup your hostname
Search for "hostname = " in the document and replace it with what you want your hostname to be.
Then, setup anti relay control so your computer isn't used by spammers(and we all hate you for it
![Wink ;) ;)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
)
Search main.cf for "mynetworks_style = " and replace it with "mynetworks_style = host" so that only your computer can send email with postfix.
Then, in terminal start postfix with "sudo postfix start" and type in your admin password.
This will start postfix and it will run for as long as your computer is running. When you restart it will not start by itself. There are threads in the unix forum, and I believe the FAQ forum for a way to start it automatically each boot.
It should be the same as Jaguar AFAIK.
In PHP you will use the mail function and it will find postfix through the installed sendmail replacement program.