senn-techProxmox Mail Gateway 9.1: Smarter Quarantine, Encrypted Backups
Proxmox Mail Gateway 9.1 (June 11, 2026) is an update focused on everyday inbox life: better quarantine handling, less tracking through external images, and client-side encrypted backups. PMG sits as a spam and virus filter before the actual mail server and checks every incoming and outgoing message.
Quarantine That Handles Shared Mailboxes
The most noticeable improvement concerns teams: quarantined emails can now be marked as “seen.” When checking a shared mailbox, users immediately recognize which messages a colleague has already reviewed — ending the duplicate review of the same list. A small change that saves time daily in shared operations.
Less Tracking Through External Images
External images in HTML emails are loaded only on request when desired. This blocks the classic tracking pixels used by senders to detect whether and when an email was opened — a small but effective privacy gain.
Backups That Encrypt Client-Side
Backups of a PMG instance to a Proxmox Backup Server can now be natively encrypted — and client-side, before the data leaves the system. Covered are the mail configuration, the self-built rule system, as well as historical and private statistics data. This means even sensitive filter rules are not stored in plaintext in the backup.
Solid Foundation
9.1 is built on Debian 13.5 “Trixie” with Kernel 7.0, SpamAssassin 4.0.2 with continuously updated rule sets, ClamAV 1.4.4, PostgreSQL 17, and ZFS 2.4.
What This Means for the Midmarket
An upstream filter like PMG takes the dirty work off the actual mail server and creates a clear control point for incoming and outgoing mail — also a building block for NIS2-compliant operation and practiced Security Awareness. Those who want to keep their email security in their own hands get a rounded, open-source tool with 9.1.
Conclusion
9.1 doesn’t shine with a major feature, but with three practical improvements: team-friendly quarantine, less tracking, encrypted backups. Exactly the kind of polish that makes a tool more pleasant and secure in daily operation.
Further Reading
What does the improved quarantine give shared mailboxes in daily use?+
Quarantined emails can now be marked as seen. Anyone checking a shared mailbox immediately recognizes which messages a colleague has already reviewed, instead of going through the same list twice. It is a small change that saves time daily in shared operations and prevents emails from being accidentally approved or ignored more than once.
How does PMG 9.1 reduce tracking through external images in HTML emails?+
External images in HTML emails are loaded only on request when desired, rather than automatically. This blocks the classic tracking pixels senders use to detect whether and when an email was opened. For the midmarket that is a small but effective privacy gain, since read receipts via tracking pixels are no longer generated silently.
Are PMG’s encrypted backups relevant for NIS2 as well?+
Yes. Backups to a Proxmox Backup Server can now be encrypted client-side, before the data leaves the system. Covered are the mail configuration, the self-built rule system, as well as historical and private statistics data. That means even sensitive filter rules are not stored in plaintext in the backup. An upstream filter like PMG also creates a clear control point for incoming and outgoing mail, supporting NIS2-compliant operation.