Not receiving email from a rewards site

They are sending me an email with a link to reset my password.  I never get the email.  I had a similar issue with usps informed delivery email that never got resolved so I changed the email destination to gmail and it worked fine.  I am now seeing the same issue with another site.  I just got off the phone with the security folks and they tell me there is no problem.  There is a problem!!!!!  This is the third site I have had this issue with and none of them have been resolved.  How many other emails am I not receiving.  Totally unacceptable.

https://forums.xfinity.com/conversations/email/usps-informed-delivery-email-not-being-delivered-anymore-to-my-xfinity-account-inbox/6574d47dcc3f661cfc864a48?commentId=666218bc09e34b487ca26585https://forums.xfinity.com/conversations/email/usps-informed-delivery-email-not-being-delivered-anymore-to-my-xfinity-account-inbox/6574d47dcc3f661cfc864a48?commentId=666218bc09e34b487ca26585