In order to track user activity, for GDPR reasons, in the ticket system there is the Last login data.
In the case where a user wants to get information from us, they “Follow” an article section. In our case the “Product Information” section.
If the user then never logs in, it looks like the user is "inactive".
If the section email notification bounces, then the user has quit the company and should somehow be purged.
I propose that some kind of report or notification should be available that a user's emails bounces, so that we can take action.

