revised "real threats" slide

[Rob Austein]

for those who haven't been able to look at the revised slides, here's
what the new "real threats" slide looks like.  note that this is all
deliberately focused on stuff that we think the audience already has
to worry about (point of slide is to get their attention so that they
listen to the rest of the presentation, not to explain every possible
threat).

==

Real threats

- Email dropboxes on servers operated by some random hosting company

   - Do you trust those MX records?

- Ops procedures depending on reverse lookups (e.g. Traceroute, SMTP
  logs)

- Bogus NAPTRs reroute VoIP

- Antispam data in the DNS