Problems with using mail() for multiple address

Hi all, I'm trying to write a form mailer for use on a friend's site. I'm using my local win95 machine for testing and phpinfo reckons I'm running PHP Version 4.0.1pl2. I'm also running Apache as my webserver. Things are going well as the IMAP functions are bloody easy to use (I'm also building a pop mail checker). The only hitch I've hit so far is this: I can send e mails easily (In fact as a test I'm sending mail from the form NOW), but I can't seem to send to more than one address at once. What is the "delimiter" for multiple address in the mail() command? I've tried comma, but I get this: "Warning: Server Error in c:\apache\htdocs\mail.php on line 17" The same results occur when I try just a space as a delimiter. What's the proper syntax? My command line is as such: mail("$sentto", "$subj", "$body", "From: $senderaddy\nReply-To: $senderaddy\nX-Mailer: PHP"); The variables are sent from a form, naturally. Anyone out there with a clue? Cheers, Bradley