SMTP with Microsoft 365

[matteu]

Hello,

Is it possible to get the configuration I need to apply for SMTP to work with M365 without basic authentication enabled ?
I don't see any "official" documentation about how to configure OAUTH.
I just find these article : https://lore.proxmox.com/all/20260602085419.271767-20-a.bied-charreton@proxmox.com/T/
and this https://forum.proxmox.com/threads/p...auth-required-working-guide-for-pve-9.180971/

Thanks for your advices.

 

[SteveITS]

If your IP doesn’t change (often?) you can use a connector. https://learn.microsoft.com/en-us/e...-send-email-using-microsoft-365-or-office-365

Note one cannot allow IPv6 addresses for it.

 

[matteu]

Hello @SteveITS
and thanks for your answer.
Unfortunately this will not be possible
Proxmox doesn t have on the roadmap to integrate modern authentication for the notification ?
I know for veeam I use it.

 

[k5map]

I took the instructions in the OP post and used Claude to setup a O365 email proxy on one of my Linux systems... this way all of my devices on my home network can send email using my O365 via the proxy on Linux. I can now eliminate the Gmail account I originally setup just for this feature.

 

[CRCinAU]

In the past, I've used the primary MX server for a destination SMTP server. It's worked for me - but YMMV when it comes to your own delivery.

I assume you're using your own domain - so you can do a `dig mx <yourdomain>` to find the primary MX server.

It might be hit and miss - depending on your connectivity, who your ISP is, if you're in a dynamic IP pool for your ISP, etc etc - but it costs nothing to try

 

[IsThisThingOn]

Is it possible to get the configuration I need to apply for SMTP to work with M365 without basic authentication enabled ?

Yes. But sometimes M365 is a PITA. But first things first.

- Are we talking about a business or private account?
- Is SMTP even allowed? You can block that by policy. You can also disable it as a user setting. Go to outlook.com and check for the user, go to admin.microsoft.com and check policies.
- They can't do SSL on port 465. You have to do STARTTLS on port 587
- Proxmox does not support modern auth? Use App Passwords instead. Go to you user settings, security and create an App Password. That thing alone changed places many times in the last few years. It is a mess. I would like to give you the official MS link to AppPasswords for private accounts https://go.microsoft.com/fwlink/?linkid=2274139 or the one for company https://support.microsoft.com/en-us...app-passwords-for-your-work-or-school-account, but that is probably also broken like most stuff for MS.