Adding custom schema to openldap

Question

I want to setup my postfix with ldap authentication. I follow this tutorial https://blog.tnyc.me/postfix-with-ldap

I need to setup a PostfixBookMailAccount but therefore i need to load that schema. I tried this one schema and adjusted the attributetype to attributetype:, same for objectclass (syntax change in newer ldap version)

Loading this schema looks good without an error.

root@openldap:~/postfix# ldapadd -Y EXTERNAL -H ldapi:/// -f /etc/ldap/schema/postfix-book.ldif 
SASL/EXTERNAL authentication started
SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth
SASL SSF: 0

But i can not choose a schema called PostfixBookMailAccount!

Any ideas?

---

Edit

Ok I found out that i have to convert the schema to a ldif first ... but doing this results in an error

root@openldap:/etc/ldap/schema# cat schema_conv.conf  
include /etc/ldap/schema/postfix-book.schema

root@openldap:/etc/ldap/schema# slaptest -f ./schema_conv.conf -F /tmp/ldif/
5d3d5e5c /etc/ldap/schema/postfix-book.schema: line 72 objectclass: AttributeType not found: "mail"

Answer 1

Ok I had to add some core schemas to be able to convert the postfix schema

include /etc/ldap/schema/core.schema
include /etc/ldap/schema/cosine.schema
include /etc/ldap/schema/inetorgperson.schema
include /etc/ldap/schema/nis.schema
include /tmp/ldif/ldap-mail-schema-master/postfix-book.schema

then slaptest did the job