To contact Comcast about email problems, you can call their customer service line at (800) XFINITY (877-339-0950). You can also access support online through the Xfinity website by going to "xfinity.com/support/contact-us" and choosing the "Chat with Xfinity" option. 
Key points about contacting Comcast for email issues:
Phone number: (800) XFINITY (877-339-0950) or 800-934-6489
Online support: Visit "xfinity.com/support/contact-us" and select "Chat with Xfinity" 
For urgent issues: Consider calling the dedicated email support line at (877) 339-0950 or 800-934-6489