I am, and have been a member of 3 FreeCycle groups in the tri-city area that I live for quite some time. I do recall vividly when they changed over to their official FreeCycle network. From then on I received few, if any notifications at all that one of the other group members had posted an ad and most of those went straight to me spam folder, though I did receive monthly notifications from the site Admins with no problems that went to my inbox.
The way I fixed it was to go back and re-register to all my groups. Not sure if this will work for you since I don't have the complex POP (that is how you have yours set up right?) email setup the way you do. Yes, I do have a Yahoo email address but I do not go through my ISP provider for it. I access it directory from the web.
I am thinking the problem lies within your email setup somehow.