Hi, Miles. We recently switched from wu-imap to dovecot, mainly to gain 
support for multiple read/write sessions per mailbox, and to reap the 
performance gains of Dovecot's indexes on old-fashioned mbox files. We've 
been very pleased with the results. In our case, we already had folks 
using a pretty consistent folder location, and we felt like it was worth 
the effort to help migrate the few stragglers in order to converge on One 
True Folder Location. But if you have some knowledge of where folks store 
their mail folders and don't want to deal with migrating everybody to one 
location, I _think_ you can simply specify multiple folder paths in 
dovecot's mail_location setting.

I also found it handy to define some extra namespaces in the dovecot 
config. This allowed folks to access the new, captive folder location 
without having to first tweak their old wu-imap-style "folder prefix" in 
their client configs:

# default namespace
namespace private {
   separator = /
   prefix =
   inbox = yes
}
# for backwards compatibility:
namespace private {
   separator = /
   prefix = Mail/
   hidden = yes
}
namespace private {
   separator = /
   prefix = ~/Mail/
   hidden = yes
}
namespace private {
   separator = /
   prefix = mail/
   hidden = yes
}
namespace private {
   separator = /
   prefix = ~/mail/
   hidden = yes
}

BTW, we also run cyrus elsewhere. It is quite lovely and a great choice 
for brand-new mail servers. And if integrating into your NIS passwd 
authentication system is your only issue, that is doable in the SASL 
configuration - we authenticate our cyrus users from NIS. But migrating a 
big existing mbox-based wu-imap service to cyrus seems pretty spooky to 
me. Dovecot is a great compromise in this case, with features and 
performance much closer to cyrus than to wu-imap, but with support for 
your existing mbox files, and the ability to seamlessly migrate formats 
later if the mood strikes you.

-Jan

On Fri, 10 Oct 2008, Miles O'Neal wrote:

> Date: Fri, 10 Oct 2008 18:01:21 -0500 (CDT)
> From: Miles O'Neal <[log in to unmask]>
> To: Scientific Linux Users <[log in to unmask]>
> Subject: imap/pop server on EL5
> 
> We're replacing our older servers, most of which
> are running EL3.  The servers we want to handle
> POP/IMAP with are running EL5.  EL4 and EL5
> dropped support for the xinetd-based imap.  Cyrus
> is way too complex, especially to tie in to the
> standard NIS passwd/shadow setup (as far as I can
> tell).  We don'twant to set up another radius
> server (we can't use the existing radius server
> for reasons irrelevant to this discussion).
>
> So I installed dovecot.  It mostly works out of
> the box, but wants to force users to migrate where
> they keep their files.  Most of our users like where
> their files are, or are at least use dto it, and
> don't want to have to learn new locations.  Their
> mail folder roots have a variety of names.  Dovecot
> is extremely configurable, but not in ways useful
> to us.
>
> What I *really* want is to just use the old imap
> server from xinetd, as it was compatible with how
> our users work.  After quite a bit of searching, I
> found exactly one rpm site with uw-imapd but it
> had a dependancy for an rpm nobody seems to have
> for EL5.
>
> SO... does anyone have an EL5 RPM of the old imapd
> for xinetd, or can anyone definitively tell me that
> dovecot will search and use multiple folder root
> dirs and point me to docs that explain how to do this?
>
> [NOTE: I tend to just say EL because we have a mix
> of SL and CentOS.]
>
> Thanks,
> Miles
>