Trouble with Office 365 SMTP

I have a client who was originally using Office 365 SMTP settings for their alarm notifications. They were using the hostname. As of last week, these stopped working and the following error was in the logs. "535 5.7.139 Authentication unsuccessful, user is locked by your organization's security defaults policy."

I had a chart with their outsourced IT team, and they essentially said Microsoft is being stricter with SMTP and that is why it is no longer working. They then had a user install Microsoft authenticator on their device, but this did not help anything.

They then had me plug in Amazon SMTP settings instead and gave me a different email to use. These worked perfectly and the users were able to receive alarm notifications in their emails again.

My question is can someone point me in the right direction of why the Microsoft settings did not work anymore. Is this fully depreciated by Microsoft or is this a case by case basis type of thing?

They might be talking about how Microsoft has been threatening to cut off regular username/password based access to SMTP ("less secure apps") for years now and are encouraging the use of OAuth instead.

If you are on a recent version of Ignition there is an OAuth client and OAuth SMTP profile that can be used.