2 - Raspberry PI Community Projects

efore Postgrey. If the client is not listed in any black-list, Whitelister tells
Postfix to accept the message; otherwise, Whitelister's reply is that it has no
opinion, and the message goes on to the next rule in the ruleset (which will
usually be the call to Postgrey). Whitelister listens on port 10000 by default.
smtpd_recipient_restrictions = permit_mynetworks,
[...]
check_policy_service inet:127.0.0.1:10000,
check_policy_service inet:127.0.0.1:60000
Since Whitelister never triggers a definitive rejection, using aggressive DNS
black-lists becomes reasonable, including those listing all dynamic IP addresses
from ISP clients (such as dynablock.njabl.org or dul.dnsbl.sorbs.net).
This can be configured with the rbl parameter in the /etc/whitelister.conf
configuration file.
11.1.5. Customizing Filters Based On the Recipient
The last two sections reviewed many of the possible restrictions. They all have their use in
limiting the amount of received spam, but they also all have their drawbacks. It is therefore
more and more common to customize the set of filters depending on the recipient. At Falcot
Corp, greylisting is interesting for most users, but it hinders the work of some users who need
low latency in their emails (such as the technical support service). Similarly, the commercial
service sometimes has problems receiving emails from some Asian providers who may be listed
in black-lists; this service asked for a non-filtered address so as to be able to correspond.
Postfix provides such a customization of filters with a “restriction class” concept. The classes
are declared in the smtpd_restriction_classes parameter, and defined the same way as smtpd_-
recipient_restrictions. The check_recipient_access directive then defines a table mapping a
given recipient to the appropriate set of restrictions.
smtpd_restriction_classes = greylisting, aggressive, permissive
greylisting = check_policy_service inet:127.0.0.1:10000,
check_policy_service inet:127.0.0.1:60000
aggressive = reject_rbl_client sbl-xbl.spamhaus.org,
check_policy_service inet:127.0.0.1:60000
permissive = permit
smtpd_recipient_restrictions = permit_mynetworks,
reject_unauth_destination,
check_recipient_access hash:/etc/postfix/recipient_access
Example 11.13
Defining restriction classes in main.cf
264 The Debian Administrator's Handbook