The default partition is the partition used when a user is created and the mailMessageStore LDAP attribute is not specified in the user entry. The mailMessageStore LDAP attribute, which specifies a user’s message store partition, should be specified in all user entries so that a default partition is not necessary. In addition, the default partition should not be changed for load balancing or any other reason. It is invalid and dangerous to change the default partition while there are still users depending on the default partition definition.
If it is absolutely necessary to change the default partition, make sure that all users on the old default partition (the one being left behind) have their mailMessageStore attribute set to their current partition (which will no longer be the default), before changing the definition of default with the configutil parameter store.defaultpartition.