Editor’s Note: April 6, 7:00pm pt – After some more investigation into this problem, it appears that the initial analysis pointing to the Content-Disposition was based on bad information. The reason that some browsers were not caching direct messages was that Twitter includes the non-standard Pragma: no-cache header in responses. Using Pragma is invalid as it is defined to be equivalent to Cache-
![Twitter Direct Message Caching and Firefox – Mozilla Hacks - the Web developer blog](https://cdn-ak-scissors.b.st-hatena.com/image/square/8f043099b608abf8384b24171faa177d3698e62e/height=288;version=1;width=512/https%3A%2F%2Fhacks.mozilla.org%2Fwp-content%2Fthemes%2FHax%2Fimg%2Fhacks-meta-image.jpg)