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A new version of the Proxmox Mail Gateway has been released. The new version based on Debian GNU/Linux 10.2 with Kernel 5.3 and uses Postfix, ClamAV, and SpamAssassin.

Here the press release:

VIENNA, Austria – November 27, 2019 – Proxmox Server Solutions GmbH has released version 6.1 of its open-source email security solution Proxmox Mail Gateway. The anti-spam and anti-virus filtering solution is a complete operating system based on the latest Debian 10.2 (Buster) with a 5.3 kernel and uses the Postfix MTA, ClamAV and SpamAssassin. Deployed between the firewall and the internal mail server the Proxmox Mail Gateway works as a full-featured mail proxy and protects organizations against spam, viruses, trojans, and phishing emails.

Proxmox Mail Gateway 6.1 comes with updated SpamAssassin rules easily adjustable in the web-based user interface, added DKIM signature support for email authentication, and a new attachment quarantine. The high availability cluster usability brings improved handling of the Configuration and Rule changes.

Main new features of Proxmox Mail Gateway include:

DomainKeys Identified Mail (DKIM) signatures: Proxmox Mail Gateway 6.1 enables DKIM signatures for outbound emails improving email authentication. DKIM signing can be comfortably done in the web interface and it helps reduce phishing and spam and improves the sender’s email deliverability. With DKIM a domain name can be associated with an email message, thus verifying its authenticity. Signing in Proxmox Mail Gateway happens after processing the email with the internal Rule System, thus ensuring that it leaves the gateway with a valid signature. Inside a cluster, the use of one common SpamAssassin selector minimizes the overhead for adding the required DNS entries.

Attachment Quarantine: Administrators can now handle quarantined attachments in the GUI. The action Remove Attachments delivers the complete email to the attachment quarantine. The administrator can inspect the quarantined attachments safely in the GUI panel and choose weather to download only selected parts of the email for further analysis or to deliver or delete the email. For safety reasons, access is restricted to administrators only.

Adjustable SpamAssassin Rule Scores via GUI: The default scoring of the SpamAssassin rule-set can be adjusted in the web interface. This allows to adapt the scoring to a specific environment, thus achieving better ham/spam detection rates. The scoring adds weight to the rules and rules, causing false positives, can be selectively disabled.

Improved handling of Configuration and Rule changes in a cluster: The filtering engine gets notified about a range of configuration changes which require a reload. The notification is propagated during the cluster sync thus reducing situations where you had to manually restart “pmg-smtp-filter”.

Experimental: Support for Before Queue filtering: Proxmox Mail Gateway 6.1 can optionally reject an email during the SMTP dialogue, instead of accepting it and silently discarding unwanted email. By answering with a permanent failure code (554), there is no need to generate a non-delivery report, as this could cause the system to get blacklisted, due to Backscatter. This is an experimental feature because it needs to be explicitly enabled in /etc/pmg/pmg.conf and is currently not compatible with the tracking center.

Further enhancements include:

Ambiguously used terms in the GUI and the documentation have been clarified.
Improved documentation of the Service Configuration Templates, see and
Emails larger than 2 MB can now be downloaded as eml from the Spam Quarantine.


Proxmox Mail Gateway is released under the GNU AGPLv3. It is available as a bare-metal ISO install with an installation wizard that automatically installs and configures all necessary components on the host eliminating manual installation configuration. The ISO install contains the full feature-set and can be downloaded at

Technical enterprise support is available from Proxmox Server Solutions. Subscription pricing starts at EUR 99 per host and year for unlimited users and provides access to the enterprise package repository with regular updates via the web interface and to support from the Proxmox team.