The Archive Shuttle Office 365 module may log the following error:
2015-02-05 08:46:57Z|3456| 36|ERROR|CallService|[email@example.com]: Error during call to Exchange Service - ServiceResponse: [Internal Server Error][InternalServerError]. 2015-02-05 08:46:57Z|3456| 52| WARN|SetBackoffEnd|Exchange/Office365 EWS Server Busy - will continue ingest after: [2015-02-05 08:51:57Z] 2015-02-05 08:46:57Z|3456| 52| INFO|CallService|[firstname.lastname@example.org]: Exchange service is busy. Sleeping thread for [30000 ms]
Office 365 module gets such message from Exchange Web Service and it means that ingest of items is postponed for some amount of time.
In order to avoid this error:
- ask Microsoft to relax throttling limit, or
- add more accounts with Impersonation Permissions, or
- change Office 365 module threads, e.g go down with item parallelism as 1 per mailbox. With higher mailbox parallelism, it is necessary to adjust EV Export Module settings as well, so the export provides enough work for the import across a higher number of containers (e.g. try 20/4 instead of 5/15).