I recently have been moving user domains from an old qmail+vpopmail server
to a new one due in large part to hugely increased spam filter load
(grumble). Anyway, I found one user with some 5+ GB of presumably all spam
in their postmaster account (which was a catch all). The new box defaults
to "set no catch-all" for exactly this kind of reason...
Here's the problem though: I saw a very significant drop in server load
when I deleted the hundreds of thousands of messages in that one user
account. The server was apparently spending a lot of time dealing with
deliveries to this one very full mailbox. This concerns me a bit since
we're running IMAP now and I could see mailboxes with thousands of
legitimate messages building up over time, and would not want to bog the
system down if I have users that never delete messages.
Does anyone know of a way to alleviate this problem without forcing
quotas? Right now we bill on disk space use, and don't set per-user or
per-domain quotas, which is popular with our customers since many of them
routinely send CAD drawings as file attachments.
I know qmail and ezmlm have hierarchical directory structures in their
queues to help with this problem, but I'm not aware of such a feature for
UNIX Systems Administrator