Specific email from Xtream Mediacom not arriving

I am not receiving emails in my Comcast inbox from my new Internet provider Xtream powered by Mediacom even though the emails are definitely sent by Mediacom. It appears that the Mediacom emails are being filtered out by Comcast, perhaps because they are a competitor? Comcast doesn’t service my new address for Internet connection. But I’m still using my Comcast email address. Because I’m no longer a Comcast customer, I can not speak to a human about this problem. Is there a solution?