[imp] Why Are All Messages Seen?

[Michael Holland]

I recently installed the latest released Horde Webmail package (1.0.1) 
on a company server.  It's working fine, except that the users are 
complaining that they can't tell new messages from old messages from 
read messages.  In short, there's no highlighting.

After looking around a bit, it seems that every row of the inbox is 
classed as "seen" regardless of whether the message is new or old, read 
or not.  Is there some secret configuration setting to get IMP to 
properly class the messages?

The mail server is POP3, if that makes any difference.

Thanks,
    Michael