Postfix SMTP relay to Office 365 for email notifications

I want CheckMK Raw to send me email notifications when there are alerts. I have read that I need to install Postfix with smarthost.

The problem is that I want to do it with a Microsoft account but the relay won’t let me send messages.

This is the configuration I have in the main.cf

Is it possible to configure CheckMK to work using the “sendmail” command instead of the “mail” command?

I don’t know if there is another way for CheckMK to send email notifications without having to use Postfix.

Thanks

Checkmk uses the main mailer on the OS to send mail. I set up sendmail on Ubuntu in the past with smtp relay for Office365 and Checkmk is still using that. But since OAuth got mandatory for Office356, I changed config and went for our alternative domain not managed by Office365 as a ‘temporary’ workaround, till I find time to figure out to do sendmail with OAuth.

So if you figure it out with sendmail, I’m interested in the solution.

It looks like you can enable SMTP AUTH on specific Office365 mailboxes according to Enable or disable SMTP AUTH in Exchange Online | Microsoft Learn

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