Not receiving e-mail from certain senders

I can send email and receive typical email like newsletters or order confirmations from sites a shop in, but there is one company that emails me repeatedly for medical orders and I am not receiving them. I had her check email spelling and even had her copy and paste my email. She sent 7 times in one day and I still don't receive any. It's NOT bouncing back to sender either. I'm wondering if I'm also missing emails from other senders as well. 

Has anyone gone through this and found a fix?  A few months back I had issues with sending and now it's receiving..