How to disable various headers

Revision as of 14:15, 10 July 2019 by Teodor Vizirov (talk | contribs) (How to disable various headers)

How to disable various headers

   KB 23867        Last updated on 2019-07-10  




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Problem

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

Resolution

1. To start with, we will first create a custom header check file, that will contain our headers that we want to ignore:

$ touch /opt/zimbra/conf/custom_header_checks


2. Once the file is created, 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'
$ zmprov mcf zimbraMtaBlockedExtensionWarnRecipient FALSE

Confirm the new header check file is picked up by zimbra:

$ postconf | grep header_checks


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

/X-Virus-Scanned/     IGNORE
/^Received: from 127.0.0.1/     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 based on your needs. 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.


4. Once you finish editing the file, restart MTA to complete the setup:

$ zmmtactl restart


Verified Against: Zimbra Collaboration 8.7, 8.8.9, 8.8.12 Date Created: 12/02/2018
Article ID: https://wiki.zimbra.com/index.php?title=How_to_disable_various_headers 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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