[exim] quota revisited

Hi

Sorry, but I still do not understand quotas correctly, even having read the
docs multiple times.
I do not know, how to rephrase them, so I repeat my questions.
Please, consider asking me, if my questions are unclear.

I know I can set "quota", "quota_warn_message" and "quota_warn_treshold" in
my local delivery transport.
(BTW, quota_is_inclusive is still default "yes")

But it seems not to work correctly:
1. If a mail arrives, which would exceed the quota, it is NOT delivered.
(correct)
2. If a mail arrives, which would exceed the threshold, it is delivered and
a warning is delivered. (correct)
3. If a mail arrives, which would exceed the quota and the threshold at the
same time, it is NOT delivered (correct) and NO WARNING is delivered.
(INCORRECT?)

Can someone give me a hint for this?

Regards,
Steffen