Chris let me know today that all of the Community Network customers who still had Cyrus mailboxes have been sorted. Most of them are now set to forward to their Exchange mailbox.
There are still about 1500 users on Cyrus, but IAM hopes to have them dealt with by the end of next week.
Once Cyrus has officially been shut down, I will archive the remaining KB articles for it.
KB Article: ONID Cyrus Mail Sunset