Disable SPF DKIM and DMRAC

Disable SPF, DKIM, and DMARC validation

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Problem

Receiving spam mails with unwanted/unknown language(s) in the message body.

Solution

Disable SPF, DKIM, and DMARC validation of incoming messages. Note: Disabling SPF, DKIM, and DMARC validation is not best practice because these records helps to identify spam messages.

Step 1:

• Load TextCat module from a custom file /opt/zimbra/data/spamassassin/localrules/custom_plugins.pre

echo -e "loadplugin Mail::SpamAssassin::Plugin::TextCat\n" > /opt/zimbra/data/spamassassin/localrules/custom_plugins.pre

Notes:

Run as zimbra user [su - zimbra]

Default file of TextCat module is /opt/zimbra/data/spamassassin/localrules/v310.pre

Step 2:

• Add below line in the file "/opt/zimbra/conf/salocal.cf.in"

ok_languages <Short code of language one>,<Short code of language two>

Example:

ok_languages en,es

Notes:

ok_languages means spam assassin will accept emails in those languages and it will add spam score to all other languages.

We can add ok_languages before the line # accept email from zimbra support and forums

Add at least two languages as accepting languages.

Step 3:

• Edit spam score for unwanted languages. Open "/opt/zimbra/data/spamassassin/rules/50_scores.cf" and edit UNWANTED_LANGUAGE_BODY

score UNWANTED_LANGUAGE_BODY <score>

Example:

score UNWANTED_LANGUAGE_BODY 4.0

Step 4:

• Verification, send an email with unwanted language in the body and check X-Spam-Status of the message in recipient side.

Example:

If message identified unwanted language, it will be tagged as

X-Spam-Status: No, score=4.59 required=6.6 tests=[DKIM_INVALID=0.1, DKIM_SIGNED=0.1, HTML_MESSAGE=0.001, NO_DNS_FOR_FROM=0.379, T_REMOTE_IMAGE=0.01, UNWANTED_LANGUAGE_BODY=4]

Reference:

https://metacpan.org/pod/Mail::SpamAssassin::Plugin::TextCat

Submitted by: Raghu Noti