WP Database Table to CSV file

You’ve got a few things wrong.

1. The first is that you are clearly in WordPress context. You should
   be using the AJAX API for this rather than including wp-load.php.
   That is virtually never the right way to do it.
2. get_results() defaults to an object, so you are going to get
   errors when you try to use the results as an array. Add ARRAY_A to
   the argument list for that function (or use object syntax)
3. Don’t hard-code the WordPress table prefix
4. $file isn’t defined
5. You have two queries when you only need one
6. Your foreach and for, and associated code, is far too
   complicated.

I don’t have your table to test with but this should be close.

function csv_pull_wpse_212972() {
  global $wpdb;
  $file="email_csv"; // ?? not defined in original code
  $results = $wpdb->get_results("SELECT * FROM {$wpdb->prefix}email_table;",ARRAY_A);

  if (empty($results)) {
    return;
  }

  $csv_output=""".implode('";"',array_keys($results[0])).'";'."\n";;

  foreach ($results as $row) {
    $csv_output .= '"'.implode('";"',$row).'";'."\n";
  }
  $csv_output .= "\n";

  $filename = $file."_".date("Y-m-d_H-i",time());
  header("Content-type: application/vnd.ms-excel");
  header("Content-disposition: csv" . date("Y-m-d") . ".csv");
  header( "Content-disposition: filename=".$filename.".csv");
  print $csv_output;
  exit;
}
add_action('wp_ajax_csv_pull','csv_pull_wpse_212972');

To “trigger” this send a request to http://sitename.com/wp-admin/admin-ajax.php?action=csv_pull. Within WordPress you can generate that (and should generate that) with $ajax_url = admin_url('admin-ajax.php?action=csv_pull');