Our newsletter mailinglist is run by an automatic program that monitors messages being sent out. If it notices that messages are persistently failing to get through to a particular e-mail address, it will eventually purge that address from the list. It does this to stop flooding the net with useless messages that bounce between machines.
However occassionally messages fail to get through for reasons related to network traffic or changes by local e-mail administrators. If this happens, it may trigger the programs purge routine. Therefore you may be dropped from the list even though you still want to receive MW. If you no longer receive MW, just send a message to firstname.lastname@example.org and we'll put you back on the list.