We're no longer able to receive external emails, however we can send out and receive internally. This is an existing setup, as the problem just started a few days ago. We have two sites: each has 1 mailbox server and 1 Hub/CAS server. Both sites are affected. I noticed an event 15004 error on each Hub/CAS server. It stated version buckets high. It was 563. Other thresholds for the queue databases were normal. Per the following article, I increased the databasemaxsize cache to 512MB, but the problem continues. http://msexchangeteam.com/archive/2008/05/14/448890.aspx
I need help ASAP as this is affecting our production environment.