Over 80% of tor traffic exits through one of 7 exit nodes. These are all high speed (100MB/sec to 300MB/sec, and one 1000MB/sec) nodes operated by the fine folks who bring you TOR.This also makes for a lot of abuse traffic from those exit nodes, so quite a few sites block them due to that.Some sites block ALL exit nodes from TOR, imgur for example.A complete list of all TOR relays and exit nodes is publically available, so that's not hard to do at all.The folks at Hushmail co-operate dilligently with law enforcement, and using their email gives you a false sense of security, and I wouldn't recommend it at all.EDIT: Current TOR relay/exit node list: hxxps://metrics.torproject.org/networkstatus.html