Enabling php5 mail function on local Apache2 server

[Andrew]

I've successfully installed the Apache2 server and php5 on my Lucid Lynx
machine. For development and testing purposes I'm running php web pages
on localhost and everything works OK except the mail() function - ie
when sending a 'form' from a web page on localhost there is no error
message but no mail is actually sent. Which parameter(s) do I need to
set to enable the mail() function, which works fine on the remote
server?

Andy