安装Proxmox Email Notification Configuration

Configuring User E-mail Address

Simple Configuration via Web UI

By default, Proxmox will try to use the domain portion of the "Email from address" as the e-mail relay server.

Advanced Configuration via CLI

To make more advanced configuration changes, like using a gmail account, you need to edit the postfix settings via command line

Sources: https://forum.proxmox.com/threads/get-postfix-to-send-notifications-email-externally.59940/,
https://www.reddit.com/r/homelab/comments/5nzmm3/setting_up_the_proxmox_email_alerts/