Horde 3 after DOVECOT upgrade

After upgrading to DOVECOT I have noticed that Horde can´t handle the Sent Mail folders feature.

Not only it can´t save messages in the folders (the same folders used by squirrel), that looks like no longer exists but also can´t create new folders from it.

The folder names used by squirrel are INBOX
INBOX.Sent
INBOX.Trash

Can you turn on horde logging (in conf.php) if you haven't already and see what errors you're getting?

Dovecot is very different in that it doesn't make all mailboxes as sub boxes of INBOX by default. The mbox to maildir conversion deals with this by creating folders that are actually named INBOX.Sent or whatever.

I'm not in front of a horde/dovecot machine that I haven't done customization on, but you might look at your horde config, specifically the servers.php file as well as the prefs.php file in $HORDE_HOME/imp/config.