You need an LDAP Connection in order to user recipient checks (for spamfinder) and auto create user (spamfinder profiles, mailsealer licenses, maildepot access rights)
At this time, the Azure AD cannot be directly used by REDDOXX, but you are probably in a hybrid setting anyway and have an active directory server.
With an Default installation of Active Directory on Microsoft Servers, the LDAP field "ProxyAddresses" that we need, is not avaible.
This LDAP field is usually part of an exchange installation, but can be activated with an active directory schema extension if necessary (depending on your microsoft server).
Microsoft already has plenty of documention examples for this (here for 2003 Server):
https://docs.microsoft.com/de-de/security-updates/windowsrightsmanagementservices/18118867
When the proxyaddresses attribute is available, you can adjust it with the attribute editor in your active directory and populate the email addresses (or use powershell comands)
On Appliance side, you configure LDAP in the realm configuration as well as in the local domains.
The Local Domain LDAP Configuration can be checked with the corresponding diagnose.
You can also use the ldap query diagnose to check if your ldap provides us with valid results
For other LDAP Connections (e.g. openldap) you can use the following documentation:
LDAP connectivity of the REDDOXX Appliance