Used under Windows only: Number of the port to connect to the server
specified with the SMTP setting when sending mail
with mail(); defaults to 25. Only available since
PHP 4.3.0.
Where the sendmail program can be found,
usually /usr/sbin/sendmail or
/usr/lib/sendmail.
configure does an honest attempt of
locating this one for you and set a default, but if it fails,
you can set it here.
Systems not using sendmail should set this directive to the
sendmail wrapper/replacement their mail system offers, if any.
For example, » Qmail
users can normally set it to
/var/qmail/bin/sendmail or
/var/qmail/bin/qmail-inject.
qmail-inject does not require any option to
process mail correctly.
This directive works also under Windows. If set, smtp,
smtp_port and sendmail_from are
ignored and the specified command is executed.