This blog post is intended to instruct administrators in critical activitives after their transition from Microsoft Online’s BPOS or Outlook Live to Office 365 Exchange Online service.
There are 3 primary tasks that must be performed post-transition (with some pre-transition preparation recommended).
1. Send-As perissions for Distribution Lists must be restored.
Due to the difference in how permissions are stored for Distribution Lists between Exchange 2007 and Exchange 2010, these permissions are dropped during the transition process. It is recommended to submit a Service Request to the Support team to get an export of these permissions prior to transition (this can be done post-transition as well, if necessary). Once you have transitioned, and have access back to your tenant with Administrative permissions, you can then set the permissions as necessary to the Distribution Lists in Office 365.
2. Send on Behalf of permissions will need to be backed up and restored.
If you are planning to run Directory Synchronization for Office 365, you will need to back up your ‘Send on Behalf of’ permissions prior to running DirSync for the first time, and then restore them after running DirSync. The reason for this is that one of the new AD attributes synced by the Office 365 Directory Sync tool (DirSync v2) is publicDelegates, which is directly responsible for keeping track of this permission set. This does not affect FullAccess or SendAs permission; those should transition successfully and not have any problems. Prior to running DirSync v2, the permissions will function successfully as all AD attributes in BPOS will transition successfully to Office 365. When DirSync v2 is run for the first time (and any Full Sync performed afterwards) it will replace the O365 AD attributes with the attributes on-premises. If you have expanded your AD schema for Excange you will have the publicDelegates attribute (if you have not extended your schema, you do not have to worry about this).
3. Proxy Addresses must be copied to AD.
In BPOS, Directory Sync (DirSync v1) does not update mailbox-enabled user objects’ proxyAddresses attribute once it has been assigned a license (and thus a mailbox). As such, most customers have taken the habit of adding proxy addresses to their BPOS users without adding them on-premises as well. Immediately post-transition, the proxy addresses will be available with no detriment to the users, however, once DirSync v2 has been run, it will overwrite the proxyAddresses attribute and remove any proxy addresses that are not in your on-premises AD (if you have not extended your AD schema for Exchange on-premises, you will not have to worry about this).