Apache 2.2 – Return 200 OK for missing images

I recently faced a problem where I needed to configure Apache to return a 200 OK when it received a request for an image that was missing, along with a custom 404 ErrorDocument which was an image. The reason for this requirement is that when Outlook 2003/2007 displays an HTML page where an image request returns a ‘404 Not Found’, it displays a broken image link icon, which is a little red ‘x’.

The solution that I ended up using was to configure mod_rewrite to look for any requests that were not valid files, links, or directories and return the custom ErrorDocument if these conditions were true. This results in a 200 OK for all requests — even on missing images. Note that this results in Apache never using the ErrorDocument 404 configured.

This configuration must be set at the directory level and not the virtual host level as this references the filesystem which requires a rewritebase to be set (which cannot be done at the virtual host level).

  RewriteEngine On
  RewriteBase /var/www/html
  RewriteCond %{REQUEST_FILENAME} !-f
  RewriteCond %{REQUEST_FILENAME} !-l
  RewriteCond %{REQUEST_FILENAME} !-d
  RewriteCond %{REQUEST_URI} !^/server-status [NC]
  RewriteRule .* /missing.jpg [L]