[imp] problem with folders

[Eben Goodman]

I am running Horde 3.0 and Imp H3 4.0.3 on Mac OSX 10.3.8

The server is running qmail and vpopmail with user's mail dirs in 
/home/vpopmail/domains/user_name/

Everything works fine except when trying to send mail.  The Save copy 
option shows an empty select list for folders to save the sent mail in, 
and upon sending it prints the following error: The folder "sent-mail" 
was not created. This is what the server said: Invalid mailbox name.

When viewing the left hand navigation, the only folder that displays is 
INBOX, and then within that are the sub folders, Drafts, Sent, 
sent-mail, Trash.  I'm not terribly familiar with how these folders are 
supposed to be setup, and looking at imp's conf.php I don't see anything 
immediately obvious concerning this...

Any advice is appreciated.

Eben