Not receiving email from vendors and newsletters I use to receive weekly.

I've realized that independent of any actions I have taken, emails from vendors I would receive have stopped.  Companies or newslaetters I sign up for have stopped and if I sign up again, I still don't receeive.. It's very frustratinf. I have even contacted companies and they can't figure out anything on their end.  I've also been told that I'm already receiving from them, when I'm not.This has been happening over several years.