Why has my email stopped syncing with my Pixel 2 phone?

At about noon on Sunday, I stopped receiving emails on my Pixel 2 phone running Android 11.  This is a comcast.net email.  I have another comcast.net email that is working properly, as well as 2 Gmail accounts that are working as they should.  So far I have:  shut down and rebooted the phone; soft reset; deleted the cache, and deleted and reinstalled the account.  That last item -- deleting and reinstalling the account -- restored the inbox to the correct state at the time of the reinstall, but no further emails were received.  In addition, I lost access to my email folders after the reinstall -- the folders are there but they are empty.  This is my primary email account and I rely on my phone for emails for days at a time, so this situation is intolerable.  How do I fix this?