When adding or editing a client, you can have the system check whether the entered email addresses or phone numbers are unique (not identical with any of the addresses or numbers in the system).
This feature can be activated or deactivated in Settings / Syst. settings / General. Specifically, you need to change the check_duplicated_contact_mails_phones setting.
By default, the feature is disabled.
If you want to enable it, you need to take into account the fact that the client form save process might take longer.
If you click on the Save button and the system finds a duplicate entry in one of the relevant fields, a pop-up window with details appears.
You can either return to the form (Cancel) or confirm the save action (Continue).
