My data sync server has been up and running good for a year now. All of a sudden it stopped syncing and I have not idea where to look. I think the problem started when 1 user was testing an email app and sent over 10,0000 emails to his account. When I look into his account using monitor I can see 9,000 pending emails. I tried vacuum and reindexing and that did not work. So I deleted his account and still Data Sync will not work, the services (connector, engine and mobilty) are all running.

Any suggestions?