I’m migrating from my old on-premise Exchange 2010 (websitepanel contolled) to a new on-premise Exchange 2016 (SolidCP controlled).

I already installed my new on-premise Exchange 2016 and SolidCP and all works well.

The two system live in totally different Forest: Exchange 2010 has own domain controller and own DNS name that are different from Exchange 2016.

Now I wish to move mailbox contents from old Websitepanel customers to new SolidCP customers.

I’ll create new accounts (not so many accounts) from scratch in SolidCP.

To migrate mailbox content I have 2 options:

1) On Exchange 2010 export mailbox content to .PST file and on Exchange 2016 import .PST file in the mailbox
This options is okay and works well but I have to do several step: Export / Copy PST File / Import. Big mailboxes and several time occurs for every move.

2) Use the migration from ECP.
I spent several hours without success to search for a solution to let this working.
The problem is that for migration to works I need to have a User of type “MailUser” (not “UserMailbox”) in the target system (Exchange 2016). So:
2.1) I created the destination new mailbox using SolidCP
This is not sufficient because migration want a destination user of type “MailUser”.

2.2) Then I deleted the mailbox (and left user) and using ECP I created a new contact “Mail User” bind to the user
This is not sufficient because migration want a valid ExchangeGuid property (the so created user ha Exchange Guid 00000000-0000-0000-0000-000000000000)
Someone has some idea to how use SolidCP to create a user of type “MailUser” so that I can migrate mailbox content to my new Exchange 2016?