[Mailman-Users] Bounces threshold never reached

[Kala Balik]

Dear list members,

two weeks ago we sent out a mailing through our six new mailman lists
with roughly 6.000 subscribers. We expected to get a number of bounces,
however, while the bounces log shows that about 600 subscribers did get
a bounce score of 1.0 or 2.0, not a single address reached the threshold
of 5.0 (or anything above 2.0) and, consequently, the admins did not get
notice about any disables or removals.

Here is my bouncing configuration:

bounce_processing: yes
bounce_score_threshold: 5.0
bounce_info_stale_after: 7
bounce_you_are_disabled_warnings: 3
bounce_you_are_disabled_warnings_interval: 7
bounce_unrecognized_goes_to_list_owner: yes
bounce_notify_owner_on_disable: yes
bounce_notify_owner_on_removal: yes

>From reading the information in the web interface my understanding of
the bounces processing is that for "bad" (i.e. unreachable) addresses
the bounces score increases EVERYDAY by 1.0 (hard bounces) or .5 (soft
bounces). Since my bounces log only displays whole numbers (either 1.0
or 2.0) I assume that most of my bounces were hard bounces (scoring 1.0
each). Therefore, constantly unreachable addresses should have reached
the threshold of 5.0 after 5 days.

Yet my log reads as if the email providers of most (about 500)
subscribers with bounces were unreachable on the day of the mailing
(kind of plausible), while the others (about 100) were "down" for two
days and then online again (not very plausible). Providers may be
unreliable sometimes, but not that unreliable. And our address base may
be good, but not that good (no permanent bouncees at all - or am I
misunderstanding the concept of permanence here - and, consequently, no
automatic unsubscribes at all).

What am I missing here? And how do I "repair" bounce processing and
automatic unsubscribe?

Thanks for your help!
Cordially,
CK