Proxmox Mail Gateway Upgrade: From 8 to 9

Introduction

Proxmox Mail Gateway (PMG) is a powerful open-source solution for email security.
In 2025, PMG 9.0 was released.
This release moves from Debian 12 Bookworm (used in PMG 8) to Debian 13 Trixie.

This article provides the steps for upgrading PMG 8 to PMG 9.

1. Preparation

• Take a full backup

pmgbackup backup /root/pmg-backup.tar.gz

If running inside a VM/Container, use snapshots or Proxmox Backup Server as well.

• Check current version

pmgversion -v

• Update all packages

apt update && apt full-upgrade -y
reboot

2. Update Repository Lists

PMG 9 is based on Debian Trixie, so you need to update your apt sources.

/etc/apt/sources.list

nano /etc/apt/sources.list

Old:

deb http://deb.debian.org/debian bookworm main contrib
deb http://deb.debian.org/debian bookworm-updates main contrib
deb http://security.debian.org/debian-security bookworm-security main contrib

New:

deb http://deb.debian.org/debian trixie main contrib
deb http://deb.debian.org/debian trixie-updates main contrib
deb http://security.debian.org/debian-security trixie-security main contrib

/etc/apt/sources.list.d/pmg-enterprise.list

Old:

deb https://enterprise.proxmox.com/debian/pmg bookworm pmg-enterprise

New:

deb https://enterprise.proxmox.com/debian/pmg trixie pmg-enterprise

If you don’t have an enterprise subscription, use the no-subscription repo:

deb http://download.proxmox.com/debian/pmg trixie pmg-no-subscription

3. Upgrade Packages

apt update
apt dist-upgrade

4. Screens You May Encounter During Upgrade

1) Package Changelog Screens

Sometimes you’ll see release notes during package upgrades (e.g., OpenSSH changes).
These are informational only.
To proceed:

• Space → scroll down
• q → quit the viewer and continue upgrade

2) Configuration File Conflicts

For example, you may see a prompt like this:

Configuration file '/etc/issue'
==> Modified (by you or by a script) since installation.
==> Package distributor has shipped an updated version.
What would you like to do about it ?  
 Y or I : install the package maintainer's version  
 N or O : keep your current version  
 D : show differences  
 Z : start a shell  

*** issue (Y/I/N/O/D/Z) [default=N] ?

Options explained:

• Y: Use the new default file from Debian
• N: Keep your current version (default & safest option)
• D: Show the differences
• Z: Drop into a shell to examine

For /etc/issue or other cosmetic files → it doesn’t matter much, but safest is N.
For critical configs (Postfix, ClamAV, PMG config) → always choose N.
Only accept new versions (Y) if you know your custom changes are unnecessary.

5. Reboot the System

reboot

6. Verify Version

pmgversion -v

Expected output:

proxmox-mailgateway: 9.0-1

7. Test & Validation

• Check if Web UI is accessible → https://<PMG-IP>:8006
• Verify mail flow
• Check quarantine reports, LDAP integration, and TLS certificates

Conclusion

In this guide, we covered upgrading from PMG 8 to PMG 9.
Summary:

1. Backup your system
2. Update packages
3. Edit sources.list to Trixie
4. Run apt dist-upgrade
5. For config prompts → N for critical files, Y optional for non-critical ones
6. Reboot and verify functionality

You should now be running PMG 9 successfully.