Install DCC for Postfix/Dovecot Spam Filtering along with SpamAssassin

Please do not try to use the ancient, modified versions of DCC software distributed by some Linux packagers. Those versions do not detect bulk mail as well as more recent versions. Installations using those old versions also have problems using the public DCC servers that often make it necessary to add their IP addresses to the blacklist that protects the public DCC servers.

The DCC source is available at dcc-servers.net and Rhyolite Software. The license on the free source is in the source as well as dcc-servers.net. The free license is intended to cover individuals and organizations including Internet service providers using DCC to filter their own mail. Organizations selling anti-spam appliances or managed mail services are not eligible for the free license.
https://www.dcc-servers.net/dcc/FAQ.html

Distributed Checksum Clearinghouse (DCC) Installation:
Open UDP_OUT port 6277 in firewall.

DCC RPM Sources:
1. https://www.mirrorservice.org/sites/dl.atrpms.net/el7-x86_64/atrpms/stable/DCC-1.3.145-25.el7.x86_64.rpm  [This will not work ]
2. https://rpmfind.net/linux/atrpms/sl7-x86_64/atrpms/stable/DCC-1.3.145-25.el7.x86_64.rpm [ Use This ]

DCC Installation:

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# yum install sendmail-milter ( already installed )
# rpm -Uvh https://rpmfind.net/linux/atrpms/sl7-x86_64/atrpms/stable/DCC-1.3.145-25.el7.x86_64.rpm
# rpm -qa | grep DCC
If DCC Installation Failed

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# yum groupinstall 'Development Tools'
Enable the DCC plugin

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# vi /etc/mail/spamassassin/v310.pre
 # DCC - perform DCC message checks.
 #
 # DCC is disabled here because it is not open source.  See the DCC
 # license for more details.
 #
 loadplugin Mail::SpamAssassin::Plugin::DCC

Add the following to /etc/mail/spamassassin/local.cf

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# dcc
use_dcc 1
dcc_home /var/dcc
dcc_path /usr/local/bin/dccproc
dcc_timeout     10
add_header all  DCC _DCCB_: _DCCR_
score DCC_CHECK 4.000
N.B:Some of them using dcc_home /etc/dcc
Other Location: /usr/libexec/dcc

Copy the below Command

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# cp /usr/bin/dccproc /usr/local/bin/dccproc
# cp /usr/bin/cdcc /usr/local/bin/
Check

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# find / -name cdcc
# which cdccTest

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# cdcc info