See case TS001146300 Problem with IMSMO. When Outlook & IMSMO is used by our clients instead of IMAP or Notes clients, initial setup with complete mail file is cumbersome. When syncing a large number of changes (e.g. when initially syncing a user's mail file), the data is sent to our SyncML clients in smaller chunks - up to 50 chunks at a time. In the IMSMO case, when this 50-part limit is reached, the client cancels the sync in order to prevent stack overflow. This means that in order to facilitate continuation of the sync, either a manual sync request must be made (as the customer observed), or Outlook client must automatically generate a new sync request. The default interval for Outlook to automatically make sync requests is 30 minutes. This is likely the case in the customer's environment, and thus they will not see more data sync down for at least 30 minutes if they do not generate a sync request during this time. The user has either to click send/receive multiple times or change the sync interval from 30 min to 5 min.
I suggest to have an improved push notification process during the initial sync process, in order to be able to receive ALL mails without user involvement.