Banned files claiming to be quarantined, but not in quarantine

[listserv.traffic at sloop.net]

So, I've had two of these:

The server gets a message with winmail.dat which is banned through the rule that blocks tnef's.
Which, while may not be exactly how I want it to act, I'm fine with it so far.

This is the "report" for the banned file:
---
No viruses were found.

Banned name: .image,.png,image001.png,image001.png
Content type: Banned
Internal reference code for the message is 21212-12/vdxXxXxXxXxX

First upstream SMTP client IP address: [12.121.212.121] xyxz-xyz.zxy.xyz.zzx.xxxzzz.com
According to a 'Received:' trace, the message originated at: [45.545.454.545],
  xyzxyzxyz at xyz.com [5.4.3.2]

Return-Path: <xyzxyzxyz at xyz.com>
From: "ABC XYZ" <xyzxyzxyz at xyz.com>
Message-ID:
  <123456789.123456789 at xyz.com>
Subject: blah blah blah blah blah blah
The message has been quarantined as: abc at def.com

The message WAS NOT relayed to:
<def at def.com>:
   250 2.7.0 Ok, discarded, id=19676-18 - BANNED: .image,.png,image001.png,image001.png
<ghi at def.com>:
   250 2.7.0 Ok, discarded, id=19676-18 - BANNED: .image,.png,image001.png,image001.png
---

So, it claims to have quarantined it - there's no file name that it quarantined it as. And if I search the quarantine directories for this message, it's simply not there.

Can someone shed some light on this?

Amavis-new 2.6.5 on Ubuntu 12.04, with Postfix and Dovecot.
Pre-accept proxy setup.
Relevent vars:
$final_banned_destiny     = D_DISCARD;
$virus_admin = 'it-ops at somewhere.zzz';
$banned_quarantine_to = 'it-ops at somewhere.zzz';

Other messages - at least all we've seen so far get quarantined properly - it just appears to happen to messages with winmail.dat attachments.

TIA
-Greg
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