I just had this happen to me twice and it's the first time this has happened to me in years. I made two stays within the past 10 days at hotels in Europe and neither emailed me the bill. The stays did post to my account however. Both did print a bill for me as well. This seems to be a problem with ex-USA hotels? I've never once had this problem w/in the USA and I stay 300+ nights a year.
-RM