Over the course of a Hybrid Migration there is a major step that occurs during the initial Hybrid Configuration Wizard. This is where the On Premises mailboxes get 'stamped' with an additional proxy address.

Generally this is their SAMAccountName or Alias, at the tenantname.mail.onmicrosoft.com. This leads a mailbox to have a possible entry looking like this.

alias@tenantname.mail.onmicrosoft.com

This is an important step as it means that the mail flow during the Hybrid Migration will work effectively. As this is stamped locally in Exchange, it will make it's way into the Azure Active Directory with the normal AADC linkage.

Problems

As the address is stamped on the account with the 'Default Address Policy' there could be a very real situation whereby some mailboxes do not get this additional proxy address on their accounts. If for some reason they do not have the policy applied then it will not appear. If they do not have the proxy address on their Azure AD account then they will definitely FAIL a migration attempt.

What this script does, is provide a way to connect via PowerShell into the Migration Wiz backend and automatically check that all the mailboxes that are in the batches do in fact have a proxy address matching the appropriate mail.onmicrosoft.com domain.

It provides a report at the end of any mailboxes that will cause you problems if the migration goes ahead.

Prerequisites

You will need to download and install the Bit Titan PowerShell SDK from this link.

https://help.bittitan.com/hc/en-us/articles/115008108267-Install-the-BitTitan-SDK

After this, the main function however is to get the connection to Office 365 running in the first place. To do this you need to start up ‘Windows Powershell ISE’ from your desktop and Run As Administrator. The running as administrator is very important as it will not connect if you don’t.

You will need to install the Microsoft Office 365 Online Sign In Assistant. You can find the executable https://www.microsoft.com/en-us/download/details.aspx?id=41950.

Also the Azure AD modules can be downloaded here https://docs.microsoft.com/en-us/powershell/azure/active-directory/install-adv2?view=azureadps-2.0. The short version of these instructions is to simply type the following command in the Powershell console

install-module azureadpreview

To import these modules into your Powershell sessions after you have installed them, type these commands in the Powershell console.

import-module msonline
 import-module azureadpreview

If this is the very first time you have run this type of script on your machine, you will need to start by executing this command as a ‘one-off’.

Set-ExecutionPolicy RemoteSigned

The new need here now is to import and install the new Exchange Online Management cmdlets. This can be done with the following commands.

Install-Module -Name ExchangeOnlineManagement
 Import-Module ExchangeOnlineManagement; Get-Module ExchangeOnlineManagement
 Update-Module -Name ExchangeOnlineManagement

Download

Download the Hybrid Pre-Flight script file - Check the attachment at the bottom of this guide.  

Running the Script

The script itself uses the location of C:\Scripts as it's main working directory, with a subdirectory from that called C:\Scripts\Logs

Using a 'Run as Administrator' PowerShell window, navigate to the C:\Scripts directory and run the 'Hybrid-PreFlightCheck.PS1' file.

As it starts, you will need to provide two sets of credentials.

1. Your Bit Titan Migration Wiz login credentials
2. The account with Admin Rights ( that you setup for the Hybrid Project ) for your Office 365 tenant

Once connected, you will be presented with a list of Migration Wiz Workgroups and Migration Wiz Customers that you can use. If you have only one workgroup it will automatically default to this. After you have selected the customer, the script will connect and read all of the mailboxes in the Hybrid Project.

You will be prompted for the 'onmicrosoft.com' prefix from your Azure Tenant. The script will then parse each of these accounts and check against your Azure Active Directory for the Proxy Addresses.

After completion, a simple CSV report will show all of the accounts that have issues with the Proxy Addresses. The reports are in the format of