Problem:
If there are too many emails in your mailbox and you changed the sorting order, Horde shows “There are no messages in this mailbox.”.
Solution:
Login to MySQL and then execute the following SQL statements:
use horde;
update horde_prefs set pref_value='a:0:{}' where pref_uid='[email protected]' and pref_name='sortpref' and pref_scope='imp';