...
my $newfilefound=0;
  $localtimenoformat=time;
for $file (@files) {
  $mdtmnoformat=$ftp->mdtm($file);
  unless ( ($localtimenoformat - $mdtmnoformat) > 3600 ) {
    $newfilefound++;
  }
}
if (not $newfilefound) {
  envia_mail();
}