[Done 1.3.9] Empty Delimeter Error on Update Order

[kanine]

I am getting the following error with 1.3.8a when updating an order status and sending out a notification. The email still goes out but the message is a bit of a concern to our operations staff:

Warning: strstr() [function.strstr]: Empty delimiter. in /home/****/****/shop/includes/functions/functions_email.php on line 103

Warning: Cannot modify header information - headers already sent by (output started at /home/****/****/shop/includes/functions/functions_email.php:103) in /home/****/****/shop/admin/includes/functions/general.php on line 21

Any help would be appreciated.

Edit: Error seems to come from this section:

      if ($module != 'xml_record') {
        if (!strstr($email_text, sprintf(EMAIL_DISCLAIMER, STORE_OWNER_EMAIL_ADDRESS)) && $to_email_address != STORE_OWNER_EMAIL_ADDRESS && !defined('EMAIL_DISCLAIMER_NEW_CUSTOMER')) $email_text .= "\n" . sprintf(EMAIL_DISCLAIMER, STORE_OWNER_EMAIL_ADDRESS);
        if (!strstr($email_text, EMAIL_SPAM_DISCLAIMER) && $to_email_address != STORE_OWNER_EMAIL_ADDRESS) $email_text .= "\n" . EMAIL_SPAM_DISCLAIMER;
      }

The bottom of the email looks like this:

Your order has been updated to the following status:
New status: Shipping
Please reply to this email if you have any questions.
Copyright (c) 2008 Zen Cart. Powered by Zen Cart
This email address was given to us by you or by one of our customers. If you feel that you have received this email in error, please send an email to sales@***.com