What format is data transferred in?
This will vary depending on your chosen hosted archive service.
For example, TransVault transfers data directly over the network to Microsoft Office 365 using the EWS protocol.
For extremely large data transfers, or where there is no existing API, a typical strategy is to store data on removable media in a neutral file format such as PST or EML files. In this case TransVault can be configured to package and name the exported data according to the conventions stipulated by the hosted vendor.
The removable media would then be shipped to the hosted service provider for ingestion.
To ensure peace of mind, TransVault creates a full report of exactly what data has been extracted from your system to be handed to the service provider. This further acts as evidence of due diligence in support of future eDiscovery requests.
Can we extract emails from Mimecast and put them into another location such as Office 365?
Mimecast does not as yet publish a public API for large scale data extraction.
You can extract a given mailbox or set of data from Mimecast by using Administrator rights to export the results of an eDiscovery search to PST or EML files. https://community.mimecast.com/docs/DOC-1365#jive_content_id_Exporting_Messages
This, however, is a very lengthy and manually intensive approach that is not suitable for large volumes.
Another approach is to request a bulk-export of emails. This data will typically presented in a single-instanced stream of emails in PST or Zipped EML files.
The challenge with this is that your emails will not exported according to individual user mailboxes and and does not preserve any folder structure.
TransVault is able to take this pool of emails and reconstruct it into separate user mailboxes. It can also create a new email folder structure based on meta data such as ‘Sender’ and ‘Date’ to give users the most meaningful way to navigate their migrated email records.
At the same time you can output data in the required format for ingestion into your new target cloud service, be it Office 365 or elsewhere.