ciao a tutti, mi sapete dire cosa significano questi due errori?

Warning: session_start(): Cannot send session cache limiter - headers already sent (output started at c:\programmi\apache group\apache\htdocs\fgf\frame-inviasoll.php:8) in c:\programmi\apache group\apache\htdocs\fgf\frame-inviasoll.php on line 9

Warning: 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 c:\programmi\apache group\apache\htdocs\fgf\frame-inviasoll.php on line 37



Grazie!