Thanks for the message. The anonymizing is not a problem. It turns out that this is almost an RFC 3464 compliant DSN and should be recognized by Mailman/Bouncers/DSN.py except for the fact that the 'action' in the Delivery Report is 'error'. This is non-compliant. RFC 3464, sec 2.3.3 defines action as:
action-value = "failed" / "delayed" / "delivered" / "relayed" / "expanded"
Thus, 'Action: error' in this DSN is non-compliant. It should be 'Action: failed'. You may wish to report this to the opensmtpd developers.
If the mean time, if you look at Mailman/Bouncers/DSN.py at line 59, you'll see
if not action.startswith('fail'): # Some non-permanent failure, so ignore this block continue
If you change that to
if not (action.startswith('fail') or action.startswith('error')): # Some non-permanent failure, so ignore this block continue
this DSN should be recognized by DSN.py. I'll be incorporating this fix for the next release.