Accurately Determining Mailbox Storage Use Prior to Migration

[David Levine]

Hi All,

Due to a unique circumstance related to an acquisition / divestiture I need to move some email data around.

I am looking to migrate the majority of a particular mailbox's content to a new tenant. Let's say everything prior to this year.

The plans / licensing for the two tenants are not the same. The source tenant is Office365 E5, and the destination is actually GoDaddy Business Premium (Office365). Point being that the source mailbox is provided 100GB storage, and the target mailbox is 50GB max. Before I start migrating data I want to get as clear a picture on source mailbox usage as possible.

Archiving on the source mailbox is not enabled.

Litigation hold on the source mailbox is enabled.

If I look at the basic Mailbox Usage reports in the source Office365 Admin Portal, I see the mailbox in question is using about 87 GB. However, since litigation hold is enabled on the mailbox I am not sure if this number includes all of the recoverable items storage and whatever else related to the hold.

If it is truly 87GB, then that is obviously larger than the 50GB I get from GoDaddy, so I might need to think of another solution. 

Appreciate any assistance / ideas...

~D

[#2]

The recoverableItems quota is separate from the "main" quota, so it doesn't count against the 100GB limit.

[#3]

Thanks for the reply;
So, when viewing the mailbox usage report, it will not reflect any of the storage being used for recoverable items?

[#4]

Nope, if you want to check that, you need to use PowerShell.