I want Horde IMP, Postfix and Dovecot to used the OpenLDAP.
There are many ways of doing this. How we can populate the LDAP data.
I will used pam_ldap as the example but I'm not going to set the Linux to used it. I just need the right format for my data inside LDAP. In this example object class is posixAccount.
I will use the PADL migrating script for /etc/passwd and /etc/shadow for migrating any data. The data need to be in the same format as /etc/passwd and /etc/shadow
More example here