[Exim] Maildir quotas?

With a bit of luck my subscriptions are now sorted out so that no-one
will get annoying bounces from the e-mail server I was having to use and
that the list will be happy with the address I am posting from.
Apologies for any inconvenience caused.

I am experimenting with 'voluntary' Maildir quotas using Exim and
Courier IMAP. Exim does seem to be enforcing its quota setting, but the
IMAP daemon doesn't.

Has anyone got any experience of this configuration? Do Exim and Courier
use the same quota method? Should I be having Exim use Courier's
delivermail ( I think that's what it is called ) to deliver messages?

The Courier documentation seems rather vague on the matter of quotas.
Any advice would be appreciated.

Thanks,

Alastair.