Find this section in php.ini file and set the appropriate settings for win or linux
Code:
[mail function]
; For Win32 only.
SMTP = 111.222.333.444
; For Win32 only.
sendmail_from = [email]me@localhost.com[/email]
; For Unix only. You may supply arguments as well (default: 'sendmail -t -i').
;sendmail_path =