How to disable various headers

Revision as of 13:59, 10 July 2019 by Teodor Vizirov (talk | contribs) (Resolution)

How to disable various headers

   KB 23867        Last updated on 2019-07-10  

(0 votes)


The aim of this wiki is to show how to remove sensitive email headers that are normally generated when sending an email.


To start with, we will first create a custom header check file, that will contain our new headers:

$ touch /opt/zimbra/conf/custom_header_checks

Once we create the file, we are going to add it to the zimbra configuration:

$ zmprov mcf zimbraMtaHeaderChecks 'pcre:/opt/zimbra/conf/postfix_header_checks  pcre:/opt/zimbra/conf/custom_header_checks'

The next step would be to populate the file with data. Below is an example of this file, with various headers that we would like to be ignored:

/X-Virus-Scanned/     IGNORE
/^Received: from     IGNORE
/^X-Originating-IP:/     IGNORE
/^X-Mailer:/     IGNORE
/^Mime-Version:/     IGNORE
/^User-Agent:/     IGNORE
/^X-Sanitizer:/     IGNORE
/^X-Spam-Status:/     IGNORE
/^X-Spam-Level:/     IGNORE
/^Message-ID:/     IGNORE
/^X-MimeOLE:/     IGNORE
/^X-MSMail-Priority:/     IGNORE
/^Received:/     IGNORE

The above headers are just an example. You can use any of these headers to hide sensitive information. But beware that some MX servers will automatically mark such emails passing through as spam. Furthermore, removing all the above information will make troubleshooting very difficult. Choose which headers you would like to remove and perform tests before implementing that on a production system.

Once you finish editing that file, run the following commands to complete the setup:

$ zmprov mcf zimbraMtaBlockedExtensionWarnRecipient FALSE
$ zmmtactl restart

Confirm by running: postconf | grep header_checks

Verified Against: Zimbra Collaboration 8.7, 8.8.9, 8.8.12 Date Created: 12/02/2018
Article ID: Date Modified: 2019-07-10

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Wiki/KB reviewed by SME1 SME2 COPY EDITOR Last edit by Teodor Vizirov
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