www.nct-technology.com

In the US you can get it here.

http://www.ees-usa.com

In the US it's $570  which is a bargain considering it's not only the
software (which does not have any hard limits) but also the hardware.

Basically you take it out of the box, hook it up to the network,
configure your domain(s) and users thereof and there you go.

The device updates it's firmware autonomus if a new release becomes
available, also updates the spam filter patterns autonomus over the
internet (up to once per hour!) hence you have nothing to do with all
these kind of things. It's fool proof enough that it's not possible to
misconfigure it so as it could be abused as an open relay or such.

The device also reliably filters malware or e-mails with other
malicious content.

Since it's an embedded device, it consumes only ~3W of electric energy
(hence you save half of it's price in a year just with the electric
power savings compared to a PC solution).

Ther is no operating system in it. Just firmware which is designed so
as no buffer over run exploits are possible. Even if we would asume
that it could be hijacked (again, that's not possible) you would not
be in trouble since the firmware simply lacks any functionality to
access the remaining parts of your lan.

Again, the device is designed for ease of use. It's made to serve up
to 200 users or ~10'000 e-mails per day which ever comes first.

I forgot to mention that there are no running costs for the spamfilter
nor for the firmware.

HTH

Markus