Concern:

You would like to reset the password mailadmin but forgot the original one.

Solution:

Login as root on your OPEN-XCHANGE server.

Replace in the following command the baseDN "dc=example,dc=org" with the
baseDN you entered during your installation.

# baseDN=dc=example,dc=org; ldappasswd -D cn=Administrator,$baseDN -h localhost -W -x uid=mailadmin,ou=people,$baseDN

(RHEL uses "Manager" as rootDN default and the users are stored beneath
ou=Users,ou=OxObjects,$baseDN)

If you don't remember your baseDN simply execute

cat /etc/openldap/ldap.conf

and read the baseDN from the line starting with "base". After executing
the command for changing the mailadmin password you will be asked for
the password you entered for the root account. If the reset of the
password of user mailadmin is succesfull you can read the newly
generated password on the command line.

Important for using RHEL:

Please note that RHEL4 has no rootDN account as default within LDAP.
Hence you have to configure it before the above description works. To do
so, you have to generate a password for the rootDN. This can be done
using "slappasswd", which generates a crypted hash of a given password.

# slappasswd
New password:
Re-enter new password:
{SSHA}MCavO+n+BWw9kghjsDDStZV/VSEC0znq

Now you have to put the created hash (your one will be different of
course) into slapd.conf

rootdn "cn=Manager,dc=example,dc=org"

# this is the crypted hash from above
rootpw "{SSHA}MCavO+n+BWw9kghjsDDStZV/VSEC0znq"

and restart the ldap service

Afterwards, the above "ldappasswd" command should work.