I have Unity 4.0(5) running Unified Messaging. We no longer get any MWI or emails when someone leaves voice message. People are still able to send and receive voice mails just fine.
Below is an event viewer message.
Failed to set message waiting lamp for Anna DeLorenzo, ext 205, switch 0, cluster 0. This cluster is currently off-line. If the extension is not on this cluster, this condition won't affect the lamp. However if it is, then this lamp must be refreshed when the cluster comes back on-line. To refresh lamps, you may use the SA for the individual mailuser or you can use UTIM for all mailusers. [0x80045B24; E_MIU_SERVER_UNAVAILABLE]
