Unlike previous versions of IMP, 4.1+ no longer contains the 'namespace', 'hierarchies', or 'folders' parameters in servers.php. Instead, namespace configuration is automatically detected from the remote server.
Unlike before where you had to manually identify the namespaces you wanted to view (via the 'hierarchies' parameter), now by default ALL namespaces visibile on the remote server will be displayed.
This may startle users of UW-IMAP when they discover that both 1) all files in the home directory may now show up in the folders list and 2) all sorts of namespaces appear (i.e. '#ftp/', '#shared/') that weren't there before.
To disable these extra namespaces and/or restrict UW-IMAP to your mail directories only (rather than your entire home directory), you will need to reconfigure (and then recompile) your imapd daemon. For detailed instructions on how you can change this parameters, please refer to docs/CONFIG in the c-client/imapd distribution.
If you can not, or do not want to, recompile your UW-IMAP server you can try using this unsupported method of setting the mail subdirectory (folder) location. Here, unsupported means primarily that the UW-IMAP authors do not support this setup - therefore Horde does not fully support this method either. However, many have reported good success with this setup. For more information on this method, refer to docs/imaprc.txt in the c-client/imapd distribution.
Create a file called /etc/c-client.cf and insert the following two lines. The last part of the second line is the subdirectory that you want the c-client to use for accessing folders (which is 'mail/' in the following example).
I accept the risk set mail-subdirectory mail
The first line is required to state that you are accepting the risk of using an unsupported configuration file. The second line sets the mail subdirectory that the c-client routines will use (in the above example, it is set to 'mail/').
Note that if you have any clients configured to use a folder prefix (e.g. 'mail/' or similar) they will now need to be reconfigured to remove this setting.