Proxmox Server Solutions has released Proxmox Mail Gateway 9.1, the new version of its open-source email gateway that filters spam and malware before it reaches your mail server. The update has been available since June 11, 2026, and is built on Debian 13.5 “Trixie” with Linux kernel 7.0 as the default.
The software stack has been brought up to date with the usual pieces of a serious antispam system: SpamAssassin 4.0.2 with continuously updated rulesets, ClamAV 1.4.4 for antivirus, PostgreSQL 17 for the database, and ZFS 2.4 for storage.
What changes in the spam quarantine
Most of the work in this release went into the quarantine interface, where administrators spend the bulk of their time. There is now support for shared mailboxes with “seen” status markers, so when several people review the same inbox they don’t duplicate audits of the same messages.
The spam score is shown in more detail. You can see both the positive and negative components that added up to classify a message at the same time, which helps you understand why an email landed where it did. Images no longer load automatically; a “Load Images” button shows them only when you decide to, a sensible choice when you’re reviewing suspicious mail. There is also a Copy Link feature so an administrator can share access to a specific quarantine.
Encrypted backups to Proxmox Backup Server
The other concrete addition is native encryption for backups sent to a Proxmox Backup Server. Encryption happens client-side, so the configuration and statistics travel and are stored encrypted. If you already run Proxmox Backup Server in your infrastructure, this fits in without extra steps.
Who it’s for
If you run mail for a company or an organization, this is the update to follow: spam filtering and quarantine auditing are daily tasks, and they have been polished here. For homelab users, Mail Gateway remains open-source and installs at no cost, whether from the ISO on bare metal, on top of an existing Debian, or as an LXC container inside Proxmox VE.
Upgrades from 8.2 or 9.0 happen through APT, with no reinstall. Paid enterprise support starts at EUR 190 per host per year, with unlimited users and domains, but the software itself carries no usage restrictions.
If you want to build out the rest of the Proxmox virtualization stack, start with our Proxmox VE guide, the hypervisor that runs the LXC containers hosting Mail Gateway.
Source
Official Proxmox press release: https://www.proxmox.com/en/about/company-details/press-releases/proxmox-mail-gateway-9-1