I haven't received any mail, nor the test email I've sent to various addresses that forward to my CESMAIL account, since 3 PM PST.

Has anyone else had this issue today?

It is working fine for me.
Have you checked your held mail? Maybe the messages are getting trapped there for some reason.
Also have you tried sending the messages direct rather than just forwarding from other addresses?

Nothing there either. I typically check my held folder to see what spammer has dictionary blasted my domains, but today there's been nothing.

What about the test message addresses directly to your SpamCop Account. Does that go through?

My test message went through within seconds: http://www.spamcop.net/sc?id=z1067319402z9...d768e140976cc1z

I did not have any Held mail overnight myself, which is unusual, but I have received 3 since 8:30 and I had my normal messages in the Inbox.

I certainly hope you're not using "catch-all" addresses on your domains. Forwarding all mail from domains with catch-alls creates unnecessary extra load on the system and has the potential to negatively impact its performance for the rest of the users. JT is very opposed to catch-alls.

DT