this is my next step:

there are 3 notifications like the one above:
- after user was not logged in for 7 days
- after user was not logged in for 14 days
- after 14 days user account will be deactivated

to prevent sending spam mails I created a custom field called "cb_notifications" which isn't shown anywhere on profiles.

This field has 3 dropdown values for notification status:
- normal (default value)
- 7days
- 14days
- inactive

After that I created some Auto Actions like the one above but with Type "Field".
When LastVisitDate is less or equal to -7 DAYS, field value is set to "7days"
When LastVisitDate is less or equal to -14 DAYS, field value is set to "14days"
When LastVisitDate is less or equal to -15 DAYS, field value is set to "inactive"

Next I've created an Auto Action to change the usergroup for users which were inactive for more than 15 days.

Also I've created Auto Actions with Trigger "onAfterLogin", to reset the "cb_notifications" value to "normal" and reset the usergroup when a user comes back. Condition: If [cb_notifications] IS NOT normal.

After all I added further conditions to the E-Mail Auto Actions to control when a notification should be sent to the user:

7 Days Notification Condition: IF [cb_notifications] IS normal
14 Days Notification Condition: IF [cb_notifications] IS 7days
Account deactivation Notification Condition: IF [cb_notifications] IS 14days
-> If [cb_notifications] IS inactive : no mails are sent to the user


Hope this explanation was understandable. English isn't my best
I'm still testing these actions, but it seems to work to only sent mails depending on a "last visit status" given on profiles.