(This may seem long and rambling, but I've not seen a proper discussion
anywhere of providing a large IMAP solution under UNIX. Both hardware and
software need to be decided on. I hope some of you that have gone this way
can share your experiences.)
Hi,
We're in the preliminary stages of planning an IMAP service. We
currently have a POP3 service running on a couple of UltraSPARC 1
boxes. Each have an external RAID array holding users email. We use
qmail on the boxes, qmail's pop3d and the Maildir delivery method.
We've been phasing out SPARCs in favour of PC's running FreeBSD.
These are some of the last SPARCs to be replaced.
Am initial plan is 3 PC's with rather large RAID storage to hold the
users email. We currently have ~32000 live email users. Of course email
will be stored on the boxes, rather than in their Netware home area or
local hard disk, as it is now. What do others use out there for user
quota, etc. on IMAP servers?
Our current setup has rather little fault tolerance. Each POP server
mounts the other's filestore over NFS. User's email clients are setup to
point to a name which will resolve to either machine. Thus a user's email
client will possibly connect to the "wrong" server and the pop3d on their
will read their email over NFS. This is a problem we never really found a
solution to, as the clients are pretty dumb. We could configure the client
to point to the correct server based on username, but we have a lot of
clients that are out of our hands. Those users just configure their client
to read from "host.x.x.x" and expect it to work.
Maybe some sort of external RAID box which is directly accessible to all
three POP/IMAP servers is a solution. This smacks of an external NFS box,
though?
I'd prefer to stick with FreeBSD, but I'm thinking that Sun stuff may
provide better fault tolerance. Any opinions or solutions?
Then comes the matter of which client to use? We'd like to stay with
qmail. The Maildir delivery mechanism is nice and efficient. However, it's
seems a problem getting IMAP servers to support it. I know the IMAP server
that comes with pine can be patched to work with Maildir, but we also
don't put our email users into the passwd file. We use the qmail
users/assign file. This funtionality doesn't seem available in the pine
IMAP server. The Cyrus server does seem to have a more modular
authentication system. Hopefully we can continue to generate some sort of
config file that'll let it work with our users. (We generate the
users/assign file ever night using scripts accessing an SQL database.)
However, cyrus probbaly won't let us use Maildir. Am I right here? What
software are others using?
Cheers for any advice.
Mark Powell - UNIX System Administrator - Clifford Whitworth Building
A.I.S., University of Salford, Salford, Manchester, UK.
Tel: +44 161 295 5936 Fax: +44 161 295 5888 www.pgp.com for PGP key
[EMAIL PROTECTED] (spell salford correctly to reply to me)
