Maximum concurrent incremental syncs is the number of connections to the Gmail or IMAP server available to perform incremental ...

Maximum concurrent incremental syncs is the number of connections to the Gmail or IMAP server available to perform incremental synchronizations. If the value is set to 10, the default value, then incremental synchronization can be performed for up to 10 mailboxes at the same time. For example, if the endpoint is configured with 50 maximum concurrent migrations and 20 maximum concurrent incremental syncs, 20 connections can be used for incremental synchronization, if necessary. The other 30 connections are reserved for initial synchronizations.