IBM AH0QXML - Lotus Domino Messaging, User Manual

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Chapter 4. Domino 6 Server anti-spam features
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The field “Desired action when a connecting host is found in a DNS Blacklist” has
3 possible options:
򐂰 Log only
When Domino finds that a connecting host is on the blacklist, it accepts
messages from the host and records the hostname and IP address of the
connecting server and the name of the site where the server was listed.
򐂰 Log and tag message
When Domino finds that a connecting host is on the blacklist, it accepts
messages from the host, logs the host name and IP address of the
connecting server, and the name of the site where the server was listed, and
adds the Notes item $DNSBLSites to each accepted message.
򐂰 Log and Reject message
When Domino finds that a connecting host is on the blacklist, it rejects the
connection and returns a configurable error message to the host.
Using the Custom SMTP error message response for rejected messages, you
can create your own error message. In the previous example, custom error
handling is enabled and will result in a delivery failure report being returned with
the text found in this field. If no custom error response is entered, the default
error message will be “
Connection denied based on policy reason .”
When utilizing the DNS Blacklist filters, you may wish to obtain additional
statistics to determine which connections are being reported as found in the DNS
Blacklist database. Domino does not enable these statistics by default.
To begin reporting the specifics on where these connections are coming from,
and in what DNSBL these hosts were found, enable the following notes.ini
variable on your SMTP server:
SMTPExpandDNSBLStats=1
Note: Domino uses IP version 4 (IPv4) addresses when querying DNS
blacklist sites to find out if a connecting host is listed. If the connecting host
has an IP version 6 (IPv6) address, Domino skips the DNSBL check for that
host.