It sounds like the email address is not correct. To look up your email address go to:
Then follow the steps. The next question will be to enter your home address.
when ever I try to establish a new acct. and try using my comcast.net email I get a message "not a valid email address.
Can you clarify---------do you mean you are trying to set up a secondary email account in Comcast? Or are you referring to something else? More details about what you are trying to do might help.
I got the same issue. This happened when I try to enter my comcast.net email address in the email address field trying to register a new account on a website. I’m 100% sure it was entered correctly. Tried on two separate devices and neither worked. Many users seem to encounter the same issue but never found a consensus on the root cause. Some said cookie/history, some mentioned outdated browser, some mentioned this means Comcast is blocking email from said website I’m trying to register. How does Comcast decide which site’s email should be blocked and how can user verify if Comcast is indeed blocking emails from a specific site?
Can you clarify------you are getting an error message from Comcast--------or from the other website? Exactly what does it say?