In week #3, I was always doing something on "Automatic Archiving".
At first, I tried to add message hooks for mod_archive, then I found it didn't work.
Finally I figured out that it's because the priority of my handler was not set correctly.
After that, I encountered another problem, the messages were passed to my handler, but just stoped there and were not passed to the other handlers. waqas told me it's because it returned true at the end of my handler.
Finally I got my handler to run.
I think I've underestimated the workload of "Automatic Archiving" that to be done. I plan to spend more time, maybe one or two weeks, on this part, because it's the fundamental of other features about archiving.