Just out of curiosity, what is the benefit of running ASSP, IMGATE,
Barracuda, and Alligate all in front of your mail system? I have
used most of these products individually in front a several
different types of mail servers, and it would seem to me there would
be little if any benefit from using several systems in succession as
they all mostly offer the same options/features --
The benefit of IMGate (an envelope rejector) as separate box as MX in
front of content-scanners is that the very expensive (in power
consumption, and in the case of commercial c-s's, in $ ($25K for
Barracuda 800 the first year) content-scanners have MUCH LESS content to scan.
IMGate blocking just for:
1) bad recipients,
2) unverifiable/undeliverable senders, and
3) greylisting
... will block 75%+ of all inbound traffic, including a huge majority
of infected messages. This means the next-hop content-scanner has to
process only 25% or less of the load that it would have to process if
facing raw Internet inbound traffic.
btw, Barracuda (which, afaics, runs postfix as IMGate does) passes
dictionary attacks straight through to the mailbox server as
Barracuda does un-cached recipient verification at the mailbox server
for ever single incoming msg. IMGate blocks dictionary attacks
totally by having its own local copy of legit recipients (doesn't
have to verify recipients back at the mailbox server).
A $600 advanced IMGate recently installed in front of a submerged
Barracuda 400 (messages delayed for 12 hours through the Barracuda)
prevented the IMGate/Barracuda customer from upgrading to a Barracuda
800 ($25K) and allowd the Barracuda 400 to keep up with the traffic
much reduced by IMGate.
Content-scanning solutions necessitate receiving 100% of every
message so it can be scanned. If you're getting charged for
bandwidth, that's a LOT of crap to eat and to pay for. IMGate gives
a huge savings in raw bandwidth and in back-end processing (content-scanning).
Of course, all of the above applies primarily to moderate- to
high-volume mail systems. Low-volume systems can get by with
throwing very powerful boxes to do all processing on the mailbox server.
And IMGate also give vastly superior outbound traffic handling with
detailed logging (answering excellently "why wasn't this message
delivered"). The logging on, eg, a closed box like Barracuda is not
available. IMGate also runs its own DNS which can be also used by
the back-end systems that will be repeating many of the DNS queries
that IMGate will have in DNS cache.
btw, IMGate "advanced" will soon be upgraded with "weighted scoring"
just like ASSP, SpamAssassin, Barracuda, Declude, Sniffer, etc while
remaining an "envelope rejector", ie, IMGate making the decision to
accept or reject a message after the RCPT TO command and before the
expensive DATA command.
Len
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