Documentation for email account provisioning

Is there any documentation that clearly explains how to set up a backend so that nextcloud email account provisioning will work ?

what is meaning of the “same user back-end”

Is the back end a mail server…an ldap server or both ?

Thanks

there is no documentation at the moment

For those of us using NextCloud on top of NethServer, it would be awesome to have an example of what to enter into the autoprovision area.