[EowynCarter]

It's not the timestamp. The T1 woudn't know anything about the timestamp unless it acctually succeed in downloading the book.

I noticed a few things with firefox that cause that. I'm now a bit confused as I can't reproduce that.

Firefox sometime says file is : application/x-crossover-epub instead of "electronic book document". That's what the T1 complain about. It expects "application/epub+zip" as mime type.

For the non techies : when the server send something back, it send information on the contant. Saying : this is html, this is a css, this is an executable.. and so on. There, the server fails to say "this is an ePub" properly. And and T1 goes "I don't know what's that file your sending me, no go."

Dropbox send that info properly, that's why it works.