Content Synchronization Engine is the server that will perform the IMAP sync with Gmail, Office...

In Avaya IX™ Messaging, for larger deployments that require synchronization with services like Gmail, Office 365, and MS Exchange, it is necessary to add remote Content Synchronization Engine(s) to handle the increased load. The specified limit for adding a remote content sync engine is one server for every 5,000 Advanced users. This ensures that the system can efficiently manage the synchronization processes for a large number of users without performance degradation.