stopped receiving emails from Groups.io. "Anti-spam service called Spamhaus labeled one of our email servers as a spam sender"

See the email I received below from a Groups.io administrator when I inquired about emails that I (and several others in my group) stopped receiving through our groups.io subscribed groups.  I entered in bold and underlined the more pertinent part of the message as it applies to xfinity/comcast.  Please assist with the resolution of this situation as quickly as possible.

Thanks!

"On Saturday afternoon, an anti-spam service called Spamhaus labeled one of our email servers as a spam sender. This caused any email service that uses Spamhaus to stop accepting email from our server. We have multiple email servers, so you still may receive some group email while not receiving other mail. Since then we have been trying to contact Spamhaus, as well as address the issues they have. That is the reason that we sent out reverification emails to many users on Sunday. Once the block is removed, all email should be sent. Resolving this issue is our highest priority.
 

In the meantime, it would be helpful to us if you could contact your email service provider and tell them that you're not receiving email because of their use of Spamhaus."