exim & courier to cyrus migration

[Marten Lehmann]

Hello,

we are currently serving about 30.000 email-addresses, where 10.000 of 
them have a pop3-mailbox and nearly 1.000 of the pop3-users also use 
imap. We have a volume of 6 GB incoming and 1,5 GB outgoing at about 
140.000 messages a day. That doesn't sound much, but our mailserver had 
high load. First we used exim & dovecot on one mailserver, then we added 
a separate mailserver for doing external deliveries. Since the 
mailserver became slow again after a few months we splitted incoming 
(exim), storage (nfs) and pop3/imap (now courier-imap because of 
nfs-locking problems with dovecot) on separate servers. While the load 
of each server is minimal right now, the overall performance when 
accessing mails through pop3/imap is not very great. I didn't expect nfs 
to be that slow, and it still is, although we switched to gigabit 
ethernet and are using fast scsi-drives only. So our next step surely 
won't be extending the current setup, but moving to cyrus murder cluster.
However, for migration I would like to ask a few things:
- How can I move all messages (stored in maildirs) to a cyrus setup?
- Can cyrus handle email-addresses like test at example.com as login name?
- Is cyrus always using the IMAP NAMESPACE extension, or is it possible 
to configure cyrus, so that a folder "Trash" isn't listed as 
"INBOX.Trash" at a LIST command, but simply as "Trash"?

Regards
Marten