Allan, I'm disappointed and feel very unloved if I don't get 1/2 a dz per day. They seem to come in waves though. And can get quite imaginative (those I even bother to open). One involved their high school athletic equipment. billion dollar basketballs, I dunno.
Some people must be too greedy or too stupid so it's worth spamming the rest of the world with this particular scam. I've read it's the 3rd largest industry in Nairobi.
