sendmail

#!/usr/bin/php
<?php
$input = file_get_contents('php://stdin');
preg_match('|^To: (.*)|', $input, $matches);
$filename = tempnam('/var/log/mail', date('ymd-his-') . $matches[1] . '.');
file_put_contents($filename, $input);

to-do.sh

vi /usr/local/bin/sendmail
# copy the above code in it

chmod 755 /usr/local/bin/sendmail

# it doesn't need to be "/var/log/mail"
# it can be any folder you like
# just change it in the sendmail-code above and here
mkdir -p /var/log/mail
chmod 777 /var/log/mail

# in php.ini change the sendmail_path
# which can also be done via .htaccess
sendmail_path = /usr/local/bin/sendmail