[pve-devel] [PATCH v2 pve-docs 11/11] notification: add docs for system mail forwarding

[Lukas Wagner <l.wagner@proxmox.com>]

Signed-off-by: Lukas Wagner <l.wagner@proxmox.com>
---
 notifications.adoc | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

diff --git a/notifications.adoc b/notifications.adoc
index c4d2931..0b00b1e 100644
--- a/notifications.adoc
+++ b/notifications.adoc
@@ -19,9 +19,10 @@ such as:
 | `fencing`         | The {pve} HA manager has fenced a node  | `error`
 | `replication`     | A storage replication job has failed    | `error`
 | `vzdump`          | vzdump backup finished                  | `info` (`error` on failure)
+| `system-mail`     | An email was sent to the local root user| `error`
 |===========================================================================
 
-In the 'Notification' panel of the datacenter view, the system's behavior can be
+In the 'Notifications' panel of the datacenter view, the system's behavior can be
 configured for all events except backup jobs. For backup jobs,
 the settings can be found in the respective backup job configuration.
 For every notification event there is an option to configure the notification
@@ -151,9 +152,22 @@ included in the group. If a group/endpoint is configured to
 use a filter, the user must have the `Mapping.Use` permission for the filter
 as well.
 
-
-
-
-
-
-
+System Mail Forwarding
+---------------------
+
+Certain local system daemons, such as `smartd`, generate notification emails
+that are initially directed to the local `root` user. {pve} will
+forward these emails to a customizable notification target.
+
+By default, these emails are sent to the email address that is configured for
+the `root@pam` user using the predefined `mail-to-root` notification target.
+However, similar to any other notification event, this behavior can be
+adjusted within the 'Notifications' panel by making changes to the
+'System Mail' setting.
+
+When the forwarding process involves an email-based target
+(like `sendmail` or `smtp`), the email is forwarded exactly as received, with all
+original mail headers remaining intact. For all other targets,
+the system tries to extract both a subject line and the main text body
+from the email content. In instances where emails solely consist of HTML
+content, they will be transformed into plain text format during this process.
-- 
2.39.2