Update -
We are continuing to investigate this issue.
Jan 24, 08:11 ACDT
Investigating -
Microsoft is currently experiencing issues affecting Microsoft 365 services, including problems with email delivery to and from Microsoft 365 accounts (Exchange Online).
Recent reports indicate a service degradation or outage impacting inbound and outbound email functionality. Users have encountered errors such as "451 4.3.2 Temporary server error" when attempting to send or receive emails, along with intermittent failures in email delivery.