MailChimp emails being blocked before reaching my account

A few months back I began not receiving from a business that send emails via MaiChimp. I had been receiving these fine for years. Something changed. Other users are experiencing the same, all have comcast.net email addresses.

I have disabled the block emails from potentially unsafe users via the comcast.web client. I am using the Comcast web client as well. The email s do not make it to SPAM or Unknown folders. 

Customer Support has not been successful.

Please advise.