# Introduce the OpenLDAP server configured by iRedMail

This is a brief introduction of the OpenLDAP server configured by iRedMail. It may help a little if you want to migrate from/to other LDAP server.

## LDAP schema files

iRedMail requires 7 LDAP schema files listed below (1-5 are shipped by OpenLDAP, no. 6 is shipped by Amavisd, no. 7 is shipped by iRedMail):

1. core.schema
2. corba.schema
3. cosine.schema
4. inetorgperson.schema
5. nis.schema
6. amavisd.schema (names are different on different linux/bsd distros)
7. iredmail.schema

If you're migrating to other LDAP server, it must include them all, otherwise you may not be able to add or update mail accounts.

## Data structure

OpenLDAP configured by iRedMail has hard-coded / predictable structure, and Postfix / Dovecot / iRedAPD /... are configured to query LDAP based on this structure.

    dc=xx,dc=xx
        |- o=domains
            |- domainName=example.com
                |- ou=Aliases
                    | mail=alias@example.com
                    | ...
                |- ou=Groups
                    | mail=list@example.com
                    | ...
                ...
                |- ou=Users
                    |- mail=postmaster@example.com
                    |- mail=xxx
                    |- ...

With this predictable structure:

- it's easy to narrow down the query scope, the narrower the scope is, the better performance you gain.

- no need to performing a query first to get the full dn of ldap object you're going to modify.

If you don't use this structure:

- you have to update Postfix/Dovecot/iRedAPD/... config files to use different query scopes and filters.

- The web-based admin panel - iRedAdmin(-Pro) - heavily relies on the predictable structure, if you use different structure, you cannot manage mail accounts with iRedAdmin(-Pro).