It's funny timing, because I just updated my page with the direct link
to Kerio 2.1.5. It's still there, just no link. Thankfully I
bookmarked the exact download URL:
http://www.kerio.com/dwn/kpf/kerio-pf-2.1.5-en-win.exe

It is also mirrored in a number of places.

As far as Kerio's and Proxo's viability, they are just as good as they
were last year and two years ago. Both have strong followings, and the
zero-down, zero payments-per-month has kept public support going. The
Kerio folks may or may not support it in the future, but that's only
an issue if a major flaw is found, and Kerio 2.1.4/2.1.5 series has
only had one known flaw so far (Compare that to ZoneAlarm or a number
of others). Kerio never really supported it fully anyway due to it
being free. However, the current situation with the new version,
4.0.8, is still not bright. The going advice by myself and others is
to disable all the "neato" features like IDS and ad-blocking, which
functionally makes 4.0.8 the same as 2.1.5. Furthermore, since Kerio
apparently completely rebuilt version 4.x (and 3) from the ground up,
there's some concern about stability even with the gee-whiz features
disabled, whereas version 2 has a proven record.
I'm not worried about Proxomitron for most of the same reasons: It has
a very strong following, and it never was really supported by it's
creator either, besides Scott Lemmon's helpfulness in some Proxo
forums.

The thing is -- and the reason why I like and recommend both Proxo and
Kerio 2.1.5 -- is that they are really very simple programs that do
their jobs well. The key to them both is how well they're configured.
They already can handle any forseeable problems. In the case of Proxo,
all the thing really does is look for certain patterns of characters
and, if it sees them, it removes them from incoming data before
passing it to the browser. So, if a scuzzy site operator figures out a
new trick to get over on people, all a Proxomitron user has to do is
figure out what the malicious string looks like (which is usually very
easy) and let Proxo know about it. Since Proxo has legions of loyal
followers who also know how to work it, it is unlikely that such
tricks will work, at least for not very long. And, pretty much the
same basic concept holds true of Kerio, too.

Sponge
Sponge's Secure Solutions
www.geocities.com/yosponge
My new email: yosponge2 att yahoo dott com