I have made a new beta with a "ExtraHeaders" keyword so that you can insert your own "Expires:" header. (The extra headers must be static, so it is probably more useful to send a Cache-Control rather than an Expires header.)
If anyone could try out whether sending expires (or cache-control) headers actually reduces network traffic, please let me know. I do not have the means to test this out at the moment.
I don't have any direct experience with Mathopd yet, but I can state with authority that when I started deliberately post-dating the expiration of my active site's <http://grc.com> static images, our incoming bandwidth utilization dropped to 1/3rd of what it had been. There was a corresponding, though much smaller, reduction in outgoing bandwidth, and our server's average connection count dropped significantly as well.
Looking at our logs, a few browsers appear to ignore the post-dated resource expirations, but the huge majority obey it and they completely stop issuing conditional "If-Modified-Since" GET requests. For sites like mine with graphical navigation toolbars on every page this can make a huge difference.
Thanks for the new "ExtraHeaders" keyword Michiel!
______________________________________________________________________ Steve.
