Some patterns for spam in my inboxes

I am lately seeing some odd patterns for spam in my various inboxes.

  • In my Frontbridge account, I regularly see spam from Gmail and never Hotmail.
  • In my Gmail account, I regularly see spam from Gmail but rarely anything else.
  • In my Yahoo account, I regularly see spam from Hotmail, but only rarely Gmail.

Those patterns are odd, I would have thought that they would have been evenly distributed.  Even more interesting is that I don't see much spam from Yahoo.