I don't like all that extra white space myself. Makes it hard to fit a good chunk of code into your window, and therefore much harder to track large numbers of nested statements. The above can be compressed into the following while not messing up readability:

if (param()) {
    my $name     = param("name");
    my $email    = param("email");
    my $phone    = param("phone");
    my $url      = param("url");
    my $requests = param("requests");

    if ($name ne "") {
        if ($email ne "") {
            if ($requests ne "") { print "very good!"; } 
            else { print "please leave a message"; }
        } 
        else { print "please enter your email"; }
    }
    else { print "please enter your name"; }
}
[download]

Or even the following, since you don't really need separate variables for each param value:

if (param()) {
    if (param('name') ne "") {
        if (param('email') ne "") {
            if (param('requests') ne "") {
                print "very good!";
            } else { print "please leave a message"; }
        } else { print "please enter your email"; }
    } else { print "please enter your name"; }
}
[download]