Is there a way to know which users (information) has changed ?
For example: I want to know if any user information (e-post, phone etc) has changed during the last month.>
(the reason for this is that I send (snail)mail to all users, so it is faster to manually change something in my layout-programs than to 'merge' personal info from CVS-files etc.
Plone does not track related changes
The solution to your woes is to periodically dump the user data (using the API) to a CSV or JSON file, then diff / compare snapshots in time.
It's not clear to me if you can use the Plone events machinery to take a snapshot after a user modification, so these are available later to be downloaded.
(Jens W. Klein)
I never used it, but in PAS there exists a
(I send the snail mail every year in januar (printed member cards, invoices etc) so I probably will not test this until much later.