Just a few days ago i was using MigrationWiz to push a customer from a hosted Exchange to Office 365. Usually when there’s no possibility of building a Hybrid Deployment, in cases when the source system is a hosted Exchange or a 3rd party e-mail platform, i recommend and use MigrationWiz as the tool to migrate the mailboxes data into Office 365, as it’s an excellent tool and easy to use, which is very handy because we tend to offload the bulk migration of the users to the customer’s IT department.
But back to the problem i encountered. As i usually do, i have configured an administrator account on the source (Hosted Exchange) and one on the destination (Office 365). Both of those administrator accounts had full access permissions to all mailboxes. I configured a connector, to use those accounts, and added some test mailboxes to the connector to start moving data and see if everything was OK. My admin account on the source was firstname.lastname@example.org and i added that account to the connector as well to migrate the data, as a test. Once i started the migration i got the following error:
Your migration failed checking source credentials. The SMTP address has no mailbox associated with it. Error: ErrorNonExistentMailbox Detail: SmtpAddress email@example.com
Well i was sure that the source mailbox existed as i was able to log into it via Outlook Web Access, so what was the problem?
The answer is actually quite simple. MigrationWiz uses Exchange Web Services (EWS) to perform the moves of the mailboxes, and the reason is better throughput!! 🙂 Read more about the MigrationWiz performance on the below link:
But again back to the problem. Those MigrationWiz EWS queries will fail if the mailbox is hidden from the Global Address List. And that was my case. Why? Well for starters you might want to hide from the global address list on the source (and even the destination), a mailbox which is in fact only used for migration purposes.
The solution? Disable the hide from address list option on the mailbox and you’re sorted.
One thing i do recommend if you’re looking at an error just like the one i have is, make sure that the mailbox actually exists. Try logging into the mailbox using Outlook Web Access. Or else you might be chasing ghosts! 🙂
I hope this post was helpful.