User`s guide

Subscribing to Blacklist Services
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■ Barracuda Spam Firewall User’s Guide
Subscribing to Blacklist Services
The BLOCK/ACCEPT-->External Blacklist page lets you subscribe to various blacklist services.
External blacklists, sometimes called DNSBLs or RBLs, are lists of Internet addresses from which
potential spam originates. The Barracuda Spam Firewall uses these lists to verify the authenticity of the
messages received. If the system receives a message from a sender on a blacklist, the message is either
blocked, quarantined or tagged depending on the blacklist settings.
By default, the Barracuda Spam Firewall uses the Barracuda blacklist service and the spamhaus.org
external blacklist service.
Blacklists can generate false-positives (legitimate messages that are blocked). However, because the
Barracuda Spam Firewall rejects such messages when they are identified, the sender will be notified and
legitimate senders will therefore know to re-send their message.
About the Blacklist Services
The following table describes each blacklist service available.
Blacklist Setting Description
Barracuda
Blacklist
Enable or disable the blacklist maintained by Barracuda Networks, which
contains servers that are manually verified for sending large amounts of spam.
Common External
Blacklists
Activate or deactivate blacklist services that are built into the Barracuda Spam
Firewall by changing the selected action for the given blacklist(s) and clicking
the Save Changes button.
Custom External
Blacklists
Enter any additional free or subscription blacklists you want to use and specify
the action you want performed. Click Add and then Save Changes when
finished.
Blacklist Using Full
Header Scan
Set to Yes to let the Barracuda Spam Firewall scan email headers for
blacklisted IP addresses.
Scanning headers can impact system performance because the Barracuda
Spam Firewall needs to do a DNS lookup for each header. For this reason, you
should only enable this feature if mail from the Internet is not delivered directly
to the Barracuda Spam Firewall.
Blacklist Service Description
sbl.spamhaus.org Spamhaus tracks the Internet's Spammers, Spam Gangs and Spam Services,
provides dependable realtime anti-spam protection for Internet networks, and
works with Law Enforcement to identify and pursue spammers worldwide
xbl.spamhaus.org To help stop the increase of spam from illegal exploits, Spamhaus released the
Exploits Block List (XBL). This list is a realtime DNS-based database of IP
addresses of illegal third-party exploits, including open proxies, worms/viruses
with built-in spam engines, and other types of trojan-horse exploits used by
spammers.
relays.ordb.org ORDB.org is the Open Relay Database. ORDB.org is a non-profit organization
that stores IP-addresses of verified open SMTP relays. These relays are likely to
be used as conduits for sending unsolicited bulk email. By accessing this list,
system administrators are allowed to choose to accept or deny email exchange
with servers at these addresses.
bl.spamcop.net SpamCop is a more aggressive spam service that often errs on the side of
blocking mail. Many mail servers can operate with blacklists in a tag-only mode,
which may be preferable when using SpamCop.