Using stmp auth for local account with PHP scripts

Hi there,

There are simple ways of relaying local mails(connection on lo0 on port 25) to a other mailserver. This is oky for logs and stuff but what's about mails created by a php on the local webserver? His do I get smtpd to still do a auth with username and pwd on lo0? Is it possible or do I need to configure the "external" addr too for this purpose?

Regards

Markus