I'm trying to setup mod_deflate to provide compressed css/js/html content, but am getting difficulty getting apache to transmit the 'content-encoding' header properly.

I've attempted the next, put into my .htaccess file within the web root:

AddOutputFilterByType DEFLATE text/html text/plain text/xml application/x-javascript application/javascript text/javascript text/css application/xml

but, checking the headers using firebug, it does not seem to be working, despite the fact that it will on my small local copy of MAMP.

Any ideas?

Which version of Apache are you currently using in your delivery server? In my opinion the AddOutputFilterByType is deprecated in versions > 2.1. However, you are able to still make this happen, only a couple of more lines:

SetOutputFilter DEFLATE

SetEnvIf Request_URI "^" no-gzip
SetEnvIf Request_URI \.(?:css|js|html)$ !no-gzip

The DEFLATE filter, includes a built-under control from the no-gzip atmosphere variable. So, this really is activating the DEFLATE filter, then turning them back for everything, then turning it back on for css|js|html files by not-setting the no-gzip filter for individuals demands.

Hope that can help.