If you need more information regarding the problem of "relationships" in an Exchange migration, please check the following page that will help you to better understand the theory and the problem.
In my Office 365 migrations experience I found 2 main problems:
- Migrate group of users that are “closed” as permissions
- Permissions cross-mailboxes only works if source and destination mailbox are on the same organization
- Re-create permissions when you move from one forest to another:
In the case that one of the “premises” is Office 365, the main problem is the first one, while the second appears only in particular situation where folder permissions where assigned using a SID History.
Starting from my first migration, BPOS time, I created a set of script to export ALL mailbox/folder/SendAs(AD)/SendOnBehalf permissions.
Having tons and tons of permissions exported to some CSV file (GBs), I create a tool to cleanup/map the data and to use this data, evaluating the correct groups of mailboxes to migrate to avoid cross-premises permissions issue. To use this set of tools I created a GitHub project where resources are shared.
The project is published at the following link https://github.com/Microsoft/emat where are also explained briefly the way to export the data and usage.
Exchange Migration Assessment Tool (EMAT) helps to create migration groups based on relationship between mailboxes (Mailbox, AD and Folder Permissions).
Refer to Documentation for up-to-date instructions
Please refer to Export Process Wiki Page for details about Export Process.
Please refer to Calculation Process Wiki Page for details about Calculation Process.
See how to build a good blacklist.csv file at the Blacklist File Wiki Page
Latest tool release can be downloaded HERE