Provide End Users with PSTs for oversize messages (4307419)

Issue
In some migrations the target environment might have a known limit related to item size. For example:
– Migrations back to Exchange might have message size limits set by administrators
– Migrations to Office 365 have limits governed by Microsoft.
In this article we will cover how to provide users with these items in PST file format
Solution
PSTs can be generated for oversize messages as follows:
1. Create a filter to select items over a specific size
2. Create a PST Link ensuring the Output Path exists and is large enough for the expected size and quantity of PSTs
3. Optionally define new PST Filename policy
4. Create a new workflow (It need only contain Native Format Close, and Native Format Rename.. but others can be added depending on the migration requirements)
5. Create a new mapping for the source container, migrating to Native Format, using the filter which was defined (and the file name policy if that was also created)
 
These steps can be done after the main migration has been done. In this situation, it is likely that the original mappings will need to have a failed item threshold configured to cope with the oversize items, otherwise they will not be able to complete stage 2.
 
These steps can also be done before the main migration. In this situation, it is likely that a ‘mirror’ policy is configured to only migrate items below the item size for the ‘real’ migration.