Yes. iCloud shows the last email received to be from 8/5. That's the same email I see on my iPhone. iCloud has not received any emails since 8/5.
No, I'm unable to receive emails through the web portal. Many attempts have been made but there are no emails beyond 8/5.
When a mail server cannot complete an email transaction with a remote server, it's common for the email to be "kicked back" with an error code. The problem here is that the Apple server never responds at all. Eventually, the email times out and gets kicked back.
I've sent emails to both the @me and @icloud address from a variety of email addresses on a variety of machines. Office 365 (cloud), Outlook (PC), Yahoo and Gmail. No email TO these addresses are delivered. It would appear emails sent FROM these addresses go out OK.