怎样开启邮件服务

我写的mail函数有警告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 h:\wwwroot\zwxr\wwwroot\cms\includes\common.inc on line 1970.因该是没有邮件服务，请问怎样开启或安装