Is your feature request related to a problem? Please describe.

We have different external work groups where the users also use the Nextcloud mail client with own email addresses. Our current issue is that we have activated the option to share and autofill names only in own group. But the mail client is getting all existing groups from Nextcloud which is from GDRP reasons very tricky. This means that every external user can see the internal groups and also the other external groups. Maybe you can integrate an option where really only the user groups will be shows where the user is a part from or disable the get groups completely.

Describe the solution you'd like

Options:

1. Show only groups where the user is a part from (or if not possible)
2. Add option on admin backend to disable the option to get the existing user groups

Describe alternatives you've considered

It would be help wheren I know the code part where I can manually remove the statement to get the nextcloud list.

Additional context

Thanks in advanced for your support!