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518 Lotus Security Handbook
Controls → Perform Anti-Relay enforcement for these connecting hosts). If the
default setting is used, internal hosts are not subject to relay controls and thus
are also exempt from blacklist checks.
Specifying how Domino handles connections from hosts found in a
DNS blacklist
You can configure Domino to take one of the following actions when it finds a
connecting host on one of the blacklists:
► Log only
► Log and tag message
► Log and reject message
In each case, the server records the following information in the Notes log: the
host's IP address and host name (if a reverse DNS lookup can determine this
information) and the name of the site that listed the host.
Note: The action you select applies to each of the specified blacklist sites.
That is, you cannot configure Domino to deny connections for hosts found on
one site's list and log the event only for hosts found on another site's list.
When tagging messages, Domino adds a special Note item to messages
received from hosts found on a blacklist. After Domino determines that a
connecting host is on the blacklist, it adds the Note item, $DNSBLSite, to each
message it accepts from the host before depositing the message in MAIL.BOX.
The value of a $DNSBLSite item is the blacklist site in which the host was found.
Administrators can use the $DNSBLSite note item to provide custom handling of
messages received from hosts listed in a blacklist. For example, you can test for
the presence of the item through the use of formula language in an agent or view
and provide conditional handling of messages that contain the item, such as
moving the messages to a special database.
When considering what action to take when Domino finds a host on the blacklist,
choose an action that's consistent with the policies of the DNS blacklist site you
use. For instance, if the service you use is very restrictive, its blacklist may
include “false positives”; that is, it may blacklist hosts that are not known sources
of spam. As a result, if you take the action of rejecting mail from any host found
on the blacklist, it could prevent the receipt of important messages.
DNS blacklist statistics
The SMTP task maintains statistics that track the total number of connecting
hosts that were found on the combined DNSBL of all sites combined, as well as
how many were found on the DNSBL of each configured site. Because the