Create private invite for chatmail server self hosting

i want to host a chatmail server but wonder if/how the invites work like the following.

so i set up the chatmail server and get local people in my area to use, i only want people in my local area to sign up for accts on my server and thought maybe theres a way to create a invite that only works for these people and maybe is only good for one sign up so i make sure the invite link does not get shared with people all over the place.

is this possible or is there some other way to get this result? i want to control who gets to create a new account. ive seen how some email platforms have a way to have manual approval for each new acct and hope maybe the same can get done here. thanks!

I believe for GitHub - chatmail/relay: chatmail service deployment scripts and docs · GitHub there is no dedicated code that allows for one-time or otherwise private invites. This is how the QR is generated:

As an alternative, this might be helpful I believe: GitHub - deltachat/mailadm: mail account administration tool for temporary and other account creation/modification · GitHub.

thanks for the info!