I recently received and email from a customer about some issues he was having with OWA WebReady document viewing. Seems that attachments that were 3mb in size could be viewed with WebReady, but a >5mb doc would result in the following error.....
I did some poking around my own Exchange server and could not find any setting in the GUI that related to this specific issue. So I pinged one of our internal Exchange aliases on this and turns out that 5mb is the default cap for viewing docs with WebReady. But! You can up the size limit by making a registry change.
On my server, the WebReadyDocumentViewing key did not exist. I added it then created the MaxDocumentInputSize DWord. For my testing, I entered 10000 decimal to set to 10mb, restarted the World Wide Web Publishing Service, and I am now able to view the document as a web page.
Now....there must be a reason why 5mb is set as the default limit. I will do some additional research to see if there are performance related issues to consider when upping this limit and post again when I find the results.