Cannot connect to mailserver (no replies)

I've got this error message when I try and connect to my mail server:

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 D:\xampplite\htdocs\xampp\php test\sendemail.php on line 28
Email sent to: ....

I have checked the php.ini file and the smtp code is not commented out.
Code in php.ini file:

[mail function]
; For Win32 only.
; http://php.net/smtp
SMTP = localhost
; http://php.net/smtp-port
smtp_port = 25

; For Win32 only.
; http://php.net/sendmail-from
sendmail_from = postmaster@localhost

I still can't seem to use the mail protocol. I'm using Xampp.