In "Appsuite" webmail ("connect.xfinity.com/appsuite/..."), see (gear icon) / Settings /
Mail / Auto Forward, check "Enable email forwarding" and fill in the destination email address to "Forward all emails to...". For starters, it would probably be a good idea to also check the "Save a copy of forwarded emails" box.
I have my comcast emails set to be forwarded to my gmail account, but when I send an email from my gmail to my comcast account I expect it to show up as forwarded to my gmail. But nothing shows up. It is received by my comcast account, but it won't foward it back to gmail. Why is this? Once again, I have already set Comcast to forward everything, checked the box, etc.