Stopped receiving emails from one European company employees on July 23, 2020

I consult with a company in Europe and for 10 years have communicated with many of their employees through my Comcast email account.  I received an email from them on July 22, but after that their emails to me did not go through. However, they receive my emails.  What can I do? It appears that several employees from the same company have the same problems sending me emails