1) Backup horde database (/hordebackup.sql). mysqldump -uadmin -p`cat /etc/psa/.psa.shadow` horde > horde_backup.sql 2) Run the below mysql queries for horde database. mysql> select * from horde_prefs where pref_uid=’test@domain.com’ and pref_name=’sortpref’; mysql> delete from horde_prefs where pref_uid=’test@domain.com’ and pref_name=’sortpref’;