Situation: The client uses Office 365 to send Mitel voicemail, Scanned documents to email, and setup some applications to send email notifications. They don’t work anymore. All venders refer to Microsoft article: How to set up a multifunction device or application to send email using Microsoft 365 or Office 365 – https://docs.microsoft.com/en-us/exchange/mail-flow-best-practices/how-to-set-up-a-multifunction-device-or-application-to-send-email-using-microsoft-365-or-office-365 . Following the instruction, they can’t make it work.
Troubleshooting: They need to follow this article:
to enable Basic Authentication on organization level.
If that doesn’t fix the problem, check this article:
to make sure the account they use also enable SMTP authentication.