php mail setup

I have it all set up(i think) right. But i still get an error message saying:
Warning: mail() [function.mail]: Failed to connect to mailserver at "localhost" port 25, verify your "SMTP" and "smtp_port" setting in php.ini or use ini_set() in Z:\users\sadako232\register\stuff.php on line 20
I know that the smtp server is set though...
php.ini
SMTP = smtp.sbcglobal.yahoo.com
When i use:
ini_set(SMTP, "smtp.sbcglobal.yahoo.com");
I get this error:
Warning: mail() [function.mail]: SMTP server response: 530 authentication required - for help go to http://help.yahoo.com/help/us/sbc/dsl/mail/pop/pop-11.html in Z:\users\sadako232\register\stuff.php on line 20
Nothing on that page helps me... Any help would be greatly appriciated,

Thanks,
ILLINI

Well it sounds like for PHP to connect and send out using that SMTP server you need to have it also authenticate itself via a username and password. I'd imagine they have it setup that way so people just don't use them to send out like spam and stuff.

but how do I set that in the ini? smtp_username and smtp_password ?

If those are options in the INI file, I'd imagine thats the ones you'd want to set.

no there is nothing in there about username and password.