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The best spam prevention techniques on
the market today use SPF in "strict mode" (and to a lesser extent mechanisms
such as ORBS) to only accept mail from someone confirmed to be who they say they
are, combined with trainable message content based filtering.
For essential information on spam
prevention using EsoMail see notes on stopping spam.
EsoMail offers advanced features to
identify undesirable spam email, block virus infected mail and prevent abuse of
your mail server by spammers. Incoming mail is scrutinised as shown in the
diagram.
SPF + Open Relay database check
SPF allows you to check that someone
sending you mail is who they say they are. EsoMail has unique features that
combines SPF with grey-listing and the allow mechanism to ensure there is
minimal impact on valid mail. In particular, using greylisting EsoMail will to
automatically start accepting mail from real mailservers, and using the allow
mechanism any valid end users whose message has been blocked is able to add
their IP address so that subsequent messages are accepted.
It is important that you have SPF
settings correctly configured. If they are not correctly configured you may
conclude that SPF is "ineffective" or "stops too much real mail".
EsoMails integrated and flexible
open relay database checking can be used enforce a
servers blacklisting or whitelisting in one or more ORBS databases. In addition
this can be used to mark messages with a header which can then be taken into
account in the ASpam "SpamDetect rating" calculation. An ORBS database is simply
a DNS server that returns a positive response if a server is listed in the
database. A variety of services are available online that can maintain blacklist
databases. Normally you would maintain your own whitelist database that
overrides the blacklist listings.
Scan messages for viruses
EsoMail has a variety of mechanisms
for integrating with external virus scanners. Such as "Mcafee"
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