Email remains in the Outbox in OWA, but in Outlook (cached mode) the folder is empty

Hello,

We have 1.200 mailbox in our Exchange Server. Several users reported that the mailbox is full. When I check the mailbox, the size of the local data is fewer that server data. In the folder Outbox of OWA there are several email´s, but these emails are not shown in folder Outbox in Outlook.

I have work around this problem disabling the cached mode, synchronizing the mailbox again and then deleting the emails from this folder (Outbox). This problem occours occasionally with several users.

Any idea?

Thanks,

Alexandre Smialoski