Issues with a blocked email

Does the postal mailing specifically say that they tried to email you at the Comcast address?  Are they getting any error message or bounce? 

You an also call Comcast security. They handle any blocking issues-----------------------

Comcast Customer Security Assurance-------------------

Normal business hours (6:00 am to 2:00 am EST, 7 days a week) 1 - 888-565-4329

Hello, @user_4r7f56 thank you for taking time to reach out over Xfinity Forums for support. You've contacted the right place for assistance, and would be happy to help answer any questions as I know receiving emails is important. I'm not sure if you saw the great information provided by our Forums expert @Latoque. 

If the email in question is blocked, a request can be made to have the email address reviewed to ensure it's safe, you may need to Google Xfinity SPA or use an incognito, as I have had customers let me know at times this link will say it's not accessible: https://spa.xfinity.com/

Email spam settings can be viewed to ensure theses aren't blocking important communications: https://www.xfinity.com/support/articles/spam-filters-and-email-blocking-new-experience

You can update email address to your email safe list: https://www.xfinity.com/support/articles/xfinity-connect-safe-list

When sending or receiving emails, if there are any error codes this document has information that goes into detail what the block is for: https://www.xfinity.com/support/articles/email-errors

Please let me know if this is helpful information, or if you are still needing assistance I can definitely investigate further.