Migrating to Office 365 from BAE Systems / Silversky Hosted Exchange

This was a fun one... not an easy process to figure out so hopefully this helps someone. To migrate away from the BAE Systems aka Silversky Hosted Exchange platform, you need to get a few things:

1. Your Office 365 organization should already be set up and ready to go (obviously)
2. An admin account in Hosted Exchange that has Full Access to the mailboxes you wish to migrate, and is a licensed user (has an Exchange package)
3. Either an Outlook installation you can use, or the testconnectivity.microsoft.com website will also do.
4. Access to the BAE Systems Exchange Provisioning Console (it's a java app)

Office 365 Setup

At this point you should have your organization created, domain added, and at least one licensed user (admin account is ok). That part of the setup is far out of scope for this guide.

Getting Admin Access

If you have just a few mailboxes, then you can just do this yourself. I highly recommend you test this with one or two mailboxes first, as i have had the built-in cusrpt@ account not work correctly.

For each user:

1. Open the user account in the provisioning console
2. Go to Packages, and edit the Exchange package
3. Launch the Mailbox Rights Management window
4. Add your admin account and grant it Full Access
5. Save all the way out, rinse and repeat

If you have a ton of mailboxes, then you may need to call support. You can launch multiple instances of the provisioning console to pipeline the requests, but i just did 500 users, so that wasn't happening. In that case, you can call support and get them to run a Powershell command to grant you access. It may take a little work to get them to escalate it, and they also may want to charge you for it. I'm not going to go over the details of the command here, you can google that one.

Starting the Migration Batch

1. Open the Exchange admin center, and head over to Recipients/Migration
2. Create a new Migration batch, "Migrate to Exchange Online"
3. Set the batch type to Cutover
4. Enter the account credentials that you set up in the previous section (the one with access to all the mailboxes)
5. It will probably give you an error at this point, that's why this guide exists. You now need to enter the Exchange server and RPC proxy server. Here we go...
   The easy part first: set the RPC proxy to exchange.postoffice.net. Now the hard part. Use either the testconnectivity.microsoft.com website, or (for the security conscious) your Outlook's Autodiscover feature. To use the former, just go to the website and enter the info, doing an Autodiscover test. To use the latter, ctrl+click on your Outlook icon, go to Test E-mail Autoconfiguration, enter the credentials and un-check the Guessmart options.
   
   At this point, regardless of the option, you will end up with the Autodiscover XML output. In here, you will see a section that says:
   
   

   <Protocol>
     <Type>EXCH</Type>
     <Server>2bd60169-a9ac-4f15-bdd4-dea1a11129a7@yourdomain.com</Server>
   

   
   You need to copy/paste the contents of the Server tag (the part that looks like an email address, including the @yourdomain.com). This is what you use for the Exchange server field.
6. Once you've done that, you do need to use the advanced/more option and set Authentication to Basic and Mailbox Permission to Full Access and hit Next
7. Name your batch, select the notification email (aren't you glad i told you to have at least one licensed user?), and you can start.

At this point, you're migrating. You can monitor the batch status from the console like you normally would. If doing a large number of mailboxes, use Powershell.