Originally Posted by Ritley572

Is the email you're using a gmail account?

I had something similar happen to me when I tried to sign up my brother for a serve account. I used all the correct info but I couldn't verify the email address, it kept prompting me to call customer service. So I did.

After a bunch of trying different browsers, clearing cache, and even waiting a few hours it turned out gmail was the culprit. I had them switch the associated email account to a yahoo account and was able to verify no problem. I realize this was with Serve and not REDCard but since they are both services using the same platform and both by AMEX this could be your issue as well.