Security is a tradeoff, there is always a choice between security and usability, a good example for this is spam filtering, almost everyone gets an overwhelming amounts of e-mail spam – fortunately there are a wide range of anti-spam solutions to help you deal with this situation.
For your personal e-mail you probably don’t care too much about an occasional lost e-mail and deleting spam manually is just too annoying – so you’ll probably prefer an aggressive filtering system, at least as long as it doesn’t block any of your friends.
From a business perspective a lost e-mail message can cost you...