Not receiving certain emails using Safari

I have been using a COMCAST email address and Apple mail for decades. In the past year or so I am not receiving authentication or confirmation emails when I am logging into some specific well established business's URL's. The latest today was Chat GPT. I was informed an authentication email was being sent to my email address but never arrived. It was not in Junk mail. Multiple attempts failed. The solution is to access the URL from Firefox. Anybody else run into this problem.?