I've never been charged and have seen over 50 at a time (I think I sent around 90 at a time, once). It does take a LONG time (hours) to both send and to get the download, if you do that. It goes a bit faster if you zip up all the files and send one single attachment, but I don't know if that makes any difference on what they'll charge, when they get around to doing so.chobitz said:AND..
are they charging yet for the email service?
I've been emailing my kindle one file at a time. It would be a heck quicker if I could do more than one at a time and mail multiple files at once.