• DCC is not installed by default because it is not open source but is still hightly recommended. See the DCC license for more details.
• DCC requires that port 6277 UDP OUT be opened if you are using a firewall.
• DCC detects if a message is bulk mail only. It does not determine if the message itself is spam.
The DCC or Distributed Checksum Clearinghouse is a system of servers collecting and counting checksums of millions of mail messages. The counts can be used by SpamAssassin to detect and reject or filter spam. Because simplistic checksums of spam can be easily defeated, the main DCC checksums are fuzzy and ignore aspects of messages. The fuzzy checksums are changed as spam evolves.
// RHEL / Centos / CloudLinux / AlmaLinux yum install gcc make // Debian / Ubuntu apt-get install gcc make wget https://www.dcc-servers.net/dcc/source/dcc.tar.Z tar xzvf dcc.tar.Z cd dcc-* ./configure --disable-dccm --bindir=/usr/bin --libexecdir=/usr/libexec/dcc --homedir=/var/lib/dcc -with-uid=popuser make make install // Centos/RHEL/CloudLinux - Apply selinux security labels to new files restorecon -Rv /usr/bin/cdcc restorecon -Rv /usr/bin/dcc* restorecon -Rv /var/lib/dcc/ restorecon -Rv /usr/libexec/dcc/
Login to Plesk and go to
Warden Anti-spam and Virus Protection ->
Plugin Settings -> Check DCC then save and press the restart button.
|Area||Test name||Description||Default scores|
||Listed in DCC (https://rhyolite.com/dcc/)||0 1.1 0 1.1|
||DCC reputation between 0 and 12 % (mostly ham)||0 -0.8 0 -0.4|
||DCC reputation between 13 and 19 %||0 -0.1 0 -0.1|
||DCC reputation between 70 and 89 %||0 0.1 0 0.1|
||DCC reputation between 90 and 94 %||0 0.4 0 0.6|
||DCC reputation between 95 and 98 % (mostly spam)||0 0.7 0 1.0|
||DCC reputation between 99 % or higher (spam)||0 1.2 0 1.4|