Sometimes users are victims of clever phishing emails sent to them. Unfortunately this opens up the use of their valuable credentials to potential hackers. These hackers can then send email using their credentials.
If Domino would have an internal counter that tracks the number of messages a single user can send in 24 hours to an internet address to a maximum number of messages, e.g. 500 messages , we could limit the problem from a large scale DSGVO disaster to something we as IT team can cope with on a smaller scale.