Unattended‑Upgrade MailReport Mode Change in Ubuntu 24.04 LTS

Goal

Configure unattended‑upgrade to send email alerts only when security updates are applied, while still allowing automatic reboots.

Constraints

MailReport supports 'on-change', 'on-err', and 'always'. The default 'always' results in excessive emails. Automatic‑Reboot can trigger silent reboots that may not notify users via systemd‑logind.

Unresolved Behavior

It is unclear how MailReport 'on-change' interacts with Automatic‑Reboot: does a reboot after a non‑security update suppress the email that would normally be sent for the change? Also, are logged‑in users notified of reboots triggered by unattended‑upgrade?

Questions

• What happens to the email alert when Automatic‑Reboot is enabled and a non‑security update triggers a reboot?
• Does systemd‑logind emit a session termination notification for reboots initiated by unattended‑upgrade, and can this be configured?
• Is there a recommended configuration that ensures security‑update notifications while still providing user awareness of reboots?