Update, backup and quarantine

[kleberpaulool]

We are going to upgrade our PMG 6 cluster to PMG 8 and we have decided that the best way to do this is to create two new servers, install PMG 8, restore the master Node backup and recreate the cluster.
However, I am particularly concerned about the quarantine of clients.
For compliance, I am required to make quarantined emails available to customers for 30 days and I know that the backup process does not export quarantined emails.
Can you help me?

 

[tom]

I suggest you do in-place upgrades, following the guides on pmg.proxmox.com.

https://pmg.proxmox.com/wiki/index.php/Upgrade_from_6.x_to_7.0
https://pmg.proxmox.com/wiki/index.php/Upgrade_from_7_to_8

 

[kleberpaulool]

Good afternoon, thanks for the response.
The question that remains is, after updating the first server, should it return to the cluster with two other server still on version 6?
Will the PMG cluster work before all three are updated?
My custom.cf has been edited. Won't I lose these customizations?