Proxmox has released version 9.0 of its Mail Gateway, a major update that upgrades the platform to Debian 13 “Trixie” and introduces Linux kernel 6.14 as the stable default.
However, before we proceed, since most people are familiar with the company primarily through their Proxmox VE offering, let’s take a moment to explain what Proxmox Mail Gateway actually does.
It is an open-source email security solution filtering out spam, viruses, and malicious content before messages reach end-users. It functions as a full mail proxy, handling both incoming and outgoing mail traffic, widely used as a dedicated layer of protection in front of existing mail servers, such as Microsoft Exchange, Postfix, or others. Now, back to the topic.
In Proxmox Mail Gateway 9.0, the security tools have been refreshed. The release includes ClamAV 1.4.3 and SpamAssassin 4.0.2, along with updated rulesets, as well as PostgreSQL 17 and ZFS 2.3.4.
A standout feature in this release is the redesigned quarantine interface. Completely rebuilt using the Rust-based Yew framework, the new UI is optimized for mobile devices, giving users a cleaner and faster way to review quarantined messages on smartphones and tablets.
Authentication has also seen significant improvements. SSO and OpenID Connect realms, first introduced in 8.2, are now fully configurable through the graphical interface. Administrators can map claims, assign default roles, and integrate seamlessly with identity management systems like Keycloak, Zitadel, or LemonLDAP::NG.
On the security front, Proxmox Mail Gateway 9.0 updates its filtering engine to match the latest MIME type definitions for Microsoft executables, ensuring that high-risk files are properly blocked. Additional hardening measures, bug fixes, and API refinements are also included.
For those upgrading from version 8.2, Proxmox provides a tested and detailed migration path to help ensure a smooth transition. The ISO installer, based on Debian 13.1, is available for fresh installs on bare metal, but the software can also run on top of Debian or inside a Proxmox VE container.
For more information, see the annoucement ot visit the release notes.
