diff --git a/mailcomment.module b/mailcomment.module
index 7c723dd..fd1429a 100644
--- a/mailcomment.module
+++ b/mailcomment.module
@@ -346,11 +346,11 @@ function mailcomment_mailhandler($node, $result, $i, $header, $mailbox) {
   }
   $to = $header->to[0]->mailbox . '@' . $header->to[0]->host;
   // If not a catchall, check only for direct matches
-  if (in_array($to, mailcomment_mailboxes())) {
+  if (in_array(strtolower($to), array_filter(mailcomment_mailboxes(), 'strtolower'))) {
     $matched = TRUE;
   }
   // Do host match for catchalls
-  else if (in_array($header->to[0]->host, $hosts)) {
+  else if (in_array(strtolower($header->to[0]->host), array_filter($hosts, 'strtolower'))) {
     $matched = TRUE;
   }
   if ($matched && $node->threading && empty($node->mailcomment['params']['error'])) {