No mail() function

Does anyone have any ideas? PHP 5.2 was compiled from source, the mail path is set to /usr/sbin/postfix in php.ini, and Apache has been restarted. The mail path shows up in phpinfo(). A trivial PHP script, written to see if mail could be sent from PHP, returns this error: *Fatal error*: Call to undefined function mail() in * /var/www/junk/testmail.php* on line *9 *The docs say that mail is a core function, like so:

    "There is no installation needed to use these functions; they are part

of the PHP core" It's a UBUNTU server, so when compiling I sudo'ed and configure / make / checkinstall (instead of make install) worked fine. However, in phpinfo() under the "standard" heading there is no :

        Path to sendmail     /usr/sbin/sendmail -t -i

like there is on our production server. Suggestions and advice will be welcomed. Regards - Miles Thompson