[Dovecot] Warn before overquota

[Joan]

Looking in the archives I found a message from dominik.saar at 1und1.de on the
16/08/06, that is asking for a system to control the overquota warnings from
within dovecot or dovecot LDA.
The proposed solution is to use exim as MTA, since it has build in support.
In my case I'm using postfix, what would be the recommended approach in that
case?
I was thinking of something like the cyrus LDA that you can with
deliverquota [ -w percent ], something like that in a quota aware LDA would
be quite useful for me.
Any proposed solution would be welcome.

Thanks