Try something like this.
#!/usr/bin/perl
use LWP::UserAgent;
$ua = LWP::UserAgent->new;
my $req = HTTP::Request->new(POST => 'http://www.site.com/submit.cgi');
$req->content_type('application/x-www-form-urlencoded');
$req->content('
[email protected]&url=http://www.site.com');
my $res = $ua->request($req);
exit;