I added this to my <processor /> element.
<mailet match="All" class="DSNBounce">
and this to my RemoteDelivery <mailet /> element:
Note: I had to add my server binded IP to "RemoteAddrNotInNetwork" matcher in order to relay bounce messages. It seems that if I use "bind" for my server then 127.0.0.1 is not enough in that matcher.
I think we should add a comment to the <bind /> element warning this fact.