> Do I need to do anything to tell Courier IMAP to enable quotas? I have > it configured to retrieve user details, including quota, from a
> PostgreSQL database. The Courier documentation suggests that each
> Maildir should have a file called maildirsize. I haven't got any of
> these. What is supposed to be responsible for creating it, the IMAP
> daemon? Exim? Me?
AFAIK, you should create that file. Courier reads the quota (both
size and file quota) from that file. I hacked courier to get the quota
from LDAP and not to use that file at all. The maildirsize file acts
as an accounting cache and its design accepts a race condition to gain
performance, which I don't like. When I found Courier IMAP, I hacked the
C source until it worked as required for me, so I have no clue concerning
its regular configuration. ;)
Exim has its own mechanism to set quota. It is more expensive to
recursively account all used resources, but not subject to race conditions
by simultaneously delivered mails. Encoding the message size in the
filename avoids stat(2) calls, which helps a lot. If you are concerned
with performance, then don't worry: The current generation of my mailbox
servers uses a dual 1 GHz PIII CPUs, 512 MB RAM and 10 IDE 40 GB disks.
The working set of 8 disks is connected to a 3ware 6800 controller,
the other two act as spare disks on the onboard IDE controller (using
Linux software RAID 10). A single CPU would be enough for regular use,
but not for load peaks. One server of that kind stores >300k mailboxes.
Exim does delivery, a heavily modified Courier IMAP and a heavily modified
Qmail POP daemon are used for message access. Works great.
