Not receiving emails from certain emails

I have been working with a couple companies for years via email for listing information, and for some reason now I am not getting the emails.  They are not going to SPAM, and aren't hitting my email box.  I have checked the settings, and they are listed as a contact in my contacts in the Xfinity/Comcast email application/website I use.  We don't use any Outlook or any other 3rd party email site to access my emails.  Please help, as this is business impacting.