we only deliver about 64000 of the 750000 or so a day inbound.
90+ as spam, fairly typical.
With an IMGate you block 70+% of that as long-hanging fruit with only
3 explicit filters:
1. bad recips
2. greylisting
3. SAV
... plus the standard sender_domain_not_found, illegal SMTP command
pipelining, relay attempts,etc.
You'd probably block close to 80% by adding IMGate weighted RBL + DNS checks.
80% of 750K = 625K msgs that:
1. are rejected before DATA command, hugely reducing your bandwidth
wasted on spam.
2. won't touch the Imail/etc box, hugely, noticeably (to your
interactive users) reducing the load on and speeding up the Imail
box, and keeping Imail from tipping over into its various
instabilities (any version of Imail). That's 625K msgs that won't
ever touch the oft-congested Imail disk.
Plus, Imail will send its outbound through IMGate where you get much
better control, better queue processing, and vastly superior logging
to assist in debugging outbound delivery problems. Imail will be able
to drop its outbound on IMGate without any any Imail queuing or DNS
lookups or deferred msgs killing the Imail queue processing.
Plus, IMGate runs its own DNS that does probably 99% of the lookups
that Imail/etc will do which will be answered from IMgate's DNS cache.
Len
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