Allow disabling mails for open slots in managed stores
Description
Many people dislike the "Warnung: Für die nächste Abholung bei hat sich noch niemand zum Abholen eingetragen". It should be possible to disable getting these Mails in the notification settings.
Impact
Less Mail spam
Proposal
The default should be to send these mails, but the mails should contain an explanation how to get rid of these. The settings to disable these mails should only be displayed as soon as you manage a store.