[SOLVED] How does PVE send email work?

[ibigbug]

I don't remember setting up any SMTP on my PVE node but magically I can receive the email from my node to my email

from the email I received I can see the header is like below

and the domain is even from my internal local domain "*.syd.home"

How is it possible that it can send the email successfully to my real email account?

Return-Path: <root@pve.syd.home>
X-Original-To: MY-REAL-EMAIL
Delivered-To: MY-REAL-EMAIL
Received: from pve.syd.home (MYIP]) by
 mailin032.protonmail.ch (Postfix) with ESMTP id 4Qt6J51HbHz7QQ5x for <MY-REAL-EMAIL>;
 Fri, 30 Jun 2023 20:25:09 +0000 (UTC)
Received: by pve.syd.home (Postfix, from userid 65534) id CAC385002E7; Sat,
  1 Jul 2023 06:25:01 +1000 (AEST)
Received: by pve.syd.home (Postfix, from userid 0) id C54865002E6; Sat,
  1 Jul 2023 06:25:01 +1000 (AEST)
Authentication-Results: mailin032.protonmail.ch; dmarc=none (p=none dis=none)
 header.from=pve
Authentication-Results: mailin032.protonmail.ch; spf=none smtp.mailfrom=pve.syd.home
Authentication-Results: mailin032.protonmail.ch; arc=none smtp.remote-ip=MYIP
Authentication-Results: mailin032.protonmail.ch; dkim=none
From: mdadm monitoring <root@pve>
To: root@pve.syd.home

 

[LnxBil]

How is it possible that it can send the email successfully to my real email account?

This is how electronic mail works:
Lookup the domain of the recipient, connect to the mailserver, deliver the mail. It can go wrong if you got grey or blacklisted, but this is how it worked in the beginning. Nowadays, there are more and more mail providers that only allow other allowed mail providers to deliver mail.

 

[ibigbug]

This is how electronic mail works:
Lookup the domain of the recipient, connect to the mailserver, deliver the mail. It can go wrong if you got grey or blacklisted, but this is how it worked in the beginning. Nowadays, there are more and more mail providers that only allow other allowed mail providers to deliver mail.

thank you - that's a good point. I think I'm so used to have that mind we need a "mail provider" to send e-mail.

 

[Dunuin]

PVE come with postfix to send mails. But you have to set up that yourself if you want to use a SMTP server as a satelite.

 

[LnxBil]

PVE come with postfix to send mails. But you have to set up that yourself if you want to use a SMTP server as a satelite.

in addtiion: It is also called smart host (depending on the google fu you want to use to find out how to configure)

 

[ibigbug]

I'm all good now as it's working with zero setup. just got surprised that it would work without setting any relay.