comcast blocking smtp25

[richb at pioneer.ci.net (Rich Braun)]

Don Levey <lug at the-leveys.us> wrote:
>   Snooping on email?  What makes you think that you're not still
> vulnerable?  They still own the hardware, up to the point it connects
> to your house.  They could, if they want, capture all the packets
> that enter/leave your home.  Sending encrypted email might help - with
> both situations.

You have to look at the various points of vulnerability, at the legal
constraints placed on network operators and gov't agencies, and at the
technical means used by unauthorized network crackers to attempt security
breaches.

If you purchase SMTP outbound relay service from someone other than your ISP,
most likely TLS encryption is supported.  It works out of the box with just
about any email client or server (other than sendmail), and provides the same
security as the https protocol.  Not 100% secure but you'd have to have
something really valuable (or really criminal) on your system to make it worth
breaking this encryption.

The points of vulnerability I can think of are:

- Your client PC, if separate from your mail server
- Your LAN mail server, if you have one
- The last-mile connection to your ISP
- Routers and switches within the ISP
- The mail relay server you use, if you smart-host outbound mail

The easiest to compromise is the client PC--various viruses and keystroke
loggers and such.  The second easiest is your LAN mail server.  The third
easiest is the mail relay.  Hardest is the TCP/IP connectivity to and within
your ISP.

An ISP like Comcast is only going to deliberately snoop your packets under a
court wiretap order.  Not something I'm concerned about, at least until the
gov't tilts much further away from my own leftish ideology.  But the main
difference between a mail server and a router is the level of logging:  you
can be reasonably certain that at least several weeks' worth of log
information (including sender/recipient email addresses) is kept on a mail
server.  Backup tapes might contain years of that information.  If you funnel
all your email through a single 3rd-party server, then someone can get at that
log information in the future.  The same is not true of TCP/IP packets:  those
are not logged anywhere until the moment a cop or cracker puts a wiretap on
your line.

Right now there is no reason to believe anyone would target me.  But suppose
some correspondent of mine turns out guilty--or merely suspected--of some
crime?  Could I then be target of an investigation?

FYI--as I have mentioned here in the past, I have been the target of a John
Doe subpoena in US District Court.  It's not fun or cheap to fend off nosy law
firms.  The target was not even me:  it was a scattershot subpoena looking to
take down someone whom a beancounter didn't want talking down a company stock
price.

It's trivial to subpoena an ISP like Verizon or Comcast for their SMTP logs. 
Don't even need a judge's signature these days, just a top-100 law firm.

-rich