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Zextras Carbonio

A Forum dedicated to Zextras Carbonio and Zextras Carbonio Community Edition
Zextras Carbonio

Official News and Announcements

News and Announcements from Zextras regarding Carbonio and Carbonio CE


[SMTP Smuggling]

This issue is a spoofing attack concerning Postfix and was discovered recently. Their developers are working to provide a fix for the issue, but you can prevent your Carbonio to be affected by following these steps.


Before actually carrying out the steps, read the article to check background information and mitigation: https://www.postfix.org/smtp-smuggling.html

In Carbonio, a modified version of Postfix 3.8.3 is used, so you do need to change only one of the two variables, smtpd_discard_ehlo_keywords.

  1. Login to your Carbonio as the root user

  2. Go to directory /opt/zextras/common/conf

    # cd /opt/zextras/common/conf


  3. Open file main.cf and search for variable smtpd_discard_ehlo_keywords=

    there should be no value provided (i.e., there’s nothing after the =, so add the word chunking. The resulting line must read:

    smtpd_discard_ehlo_keywords = chunking


  4. Save the file and run, as the zextras user, the command

    # su - zextras -c "zmmtactl reload"

Carbonio CE - Feedback Survey

We’d love to hear about your experience of using Carbonio CE and any feedback you may have. 𝐏𝐥𝐞𝐚𝐬𝐞 𝐫𝐞𝐠𝐢𝐬𝐭𝐞𝐫/𝐥𝐨𝐠 𝐢𝐧 𝐭𝐨 𝐚𝐜𝐜𝐞𝐬𝐬 𝐭𝐡𝐞 𝐟𝐞𝐞𝐝𝐛𝐚𝐜𝐤 𝐬𝐮𝐫𝐯𝐞𝐲 𝐟𝐨𝐫𝐦. 𝐓𝐡𝐚𝐧𝐤 𝐲𝐨𝐮!