KI 0870 Is Exchange Online secure?

Yes, it is secured on Microsoft's high security data centers, both against digital and physical intrusion.

Data is always stored in two physical locations. If one location becomes unstable or inaccessible, traffic will automatically be directed to the next location. At the same time, replication of the data to a third location starts to ensure that the data is always replicated in two locations.

You can read more about this:

Microsoft and ISO / IEC 27001
How Exchange Online secures your email secrets
How Exchange Online uses TLS to secure email connections

UiB has a data processor agreement with Microsoft. The data in Exchange Online for UiB is physically stored in Microsoft's data centres in the EU.

We are using multi-factor authentication to Microsoft 365 services for all users.

Because of this, only email programs and apps that support modern authentication can be used against Exchange Online. (Older protocols such as POP, IMAP or ActiveSync may therefore no longer be used.)