Ran into an interesting situation with one customer where they were using two Unity connection boxes for load balancing purposes. Seven ports were assigned to Pub CUC and some eight ports were assigned to Sub CUC. Customer reported an issue that quite a few users are having an issue where when they press message button on their phone, they are getting a message ‘your mailbox is full’ even though the mailbox has no or some messages. This was a strange issue. First we thought it has to do somethig with the secondary server which was installed recently. I jumped onto some affected users and found their mailbox size in “negative”. Never before I saw a mailbox in negative. Searched around and found its a bloody bug hitting the Unity connection server.
More detail about the bug:
Bug Id: CSCtc32553
Symptom: When they try to retrieve message from TUI they get the message indicating the mailbox is full. The user had nomessages. Checking the mailbox information for that subscriber I could see the following:
number of messages: 0
size: -3313293
Creation Date: 2009-01-10
There are no diagnostics or reporting in CUC that will provide more information about how the negative mailbox size occur.
CUC should have capabilities to log mailbox activity to allow us to track down what’s going wrong and enhancing csp_MailnboxesRefreshSize so mailboxes with negative counts are automatically updated. Possibily reviewing the viability to post alerts to the Application Event viewer for mailboxes with negative counts.
First found in Cisco Unity Connection version: 7.0 (1)
Workaround:
Run the following command by doing an SSH to Unity connection box:
admin:run cuc dbquery unitymbxdb1 execute procedure csp_MailboxesRefreshSize()
Rows: 0
admin:
This will bring the mailbox Size back to Positive.
voiceonbits.com 
win!
thank you sir