Relay Access Denied while sending email

I have configured microsoft 365 outlook with erpnext, and now it is working fine if i am sending with in the same domain, when i try to send email to other mail domain apart from my company domain i am getting below error

i want to send updates to my customer through notification, but it is not happening due to this error

Abrar PV

The error message says… “Empty Certificate”…which implies a TLS certificate problem