Simple email validation problem

[AS]on (release) {

if (!form.length || form.indexOf("@") == -1 || form.indexOf(".") == -1) { 
message = "Please enter a valid E-mail address"; 

} else { 

loadVariablesNum("mail.php", "0", "POST"); 
message = "Sending..."; 
}

}
[/AS]

even when its a valid email address it still gives the invalid email message. any ideas?