I recently stumbled across this quite by accident.......

Australian ISP bigpond.com Has a "security" feature that disables an email account for 3-4 hours after 3 unsuccesful attempts at gainning entry.

You would think that this would be more of a hinderence rather than a helpful feature. It's quite easy to see how something like this could be abused. It would be quite simple to prevent someone from accessing their email account if you were the type of person to do such things.......Anyway, food for thought.....