Convert Legacy Mailbox to User Mailbox in Exchange 2007

After an upgrade from Exchange 2003 to Exchange 2007, you should immediately uninstall the Exchange System Manager (ESM) on any desktop in your organisation. This is because the ESM enriches your Active Directory Users And Computers with some Integrated Exchange Tabs. These tabs, that come with ESM 2003, do not work with Exchange 2007. And if they do work, you should not use them 🙂

A known problem that could occur is when you mail-enable a user on an Exchange 2007 server by using the Active Directory Users and Computers. When you right-click a user and mail-enable it with “Exchange Tasks”, you actually create a Legacy Mailbox instead of a User Mailbox. A Legacy Mailbox stands for an Exchange 2003 mailbox: it will work on an Exchange 2007 server, but you will miss some features, provided by Exchange 2007.

If you happen to have a LegacyMailbox on an Exchange 2007 server, you can upgrade or convert it to a User Mailbox by using the shell command

Set-Mailbox -id Old-Mailbox -ApplyMandatoryProperties

In this command, “Old-Mailbox” stands for the Alias of the mailbox’ owner, i.e. “peter.petrelli”. After executing the command, the mailbox should be converted from Legacy to user in about 20 seconds.

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Thanks. Google is my friend and now you are too. I needed to know that command and I appreciate you posting it.

Jampong Ulupong

nice choice of name… Peter Petrelli… is that the guy from the HEROES tv series?


Can this be used to convert multiple legacy mailboxes to user mailboxes at the same time?


Wow, and i used to move the mailbox back to 2003 and then to 2007 to repair it,
you can always use powershell and convert all of the legacy mailboxes in Exchange 2007 to user 🙂

Get-Mailbox -filter { RecipientTypeDetails -eq “LegacyMailbox” } | Set-Mailbox -ApplyMandatoryProperties


Good Call. Nice one 🙂


Extremely useful article, thank you very much.



What if the mailbox is active with around 1 GB data? Will thi command still update legacy mailbox to user??


just an FYI that this was a GREAT article, OWA is one of the things that stops working and this fixed the problem perfectly!


Has anyone ever seen this fail? I’m working on a migration of 25000 users, and while we’re in the middle of migration, I’ve had several OU administrators incorrectly create 2007 mailboxes with the 2003 tools, creating “Legacy mailbox” type objects… I have ALWAYS been able to fix them, until now, when I have one specific mailbox that I get: Set-Mailbox : Active Directory operation failed on . This error is not retriable. Additional information: Insufficient access rights to perform the operation. Active directory response: 00002098: SecErr: DSID-03150A45, problem 4003 (INSUF F_ACCESS_RIGHTS), data 0 I have moved the user back to… Read more »


Steve: 4003

Hello Steve,

I’m not aware of a problem the way you described, but you could try to add extra security settings to the user, from which the mailbox fails.
In this post, I describe a completely different problem, but it has the same error text. 🙂 Maybe it helps you trying to solve the problem. Good luck!
If this helped you out (or not), please leave another comment. Thnx 🙂


Thanks for this, just got me out of a jam with one of my clients.




Great!!!!!!,It is very useful…


Thank you… our old sys admin never bothered to do this.

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