Set-MailboxUser fails when processing non-initialized mailboxes

[nicwaller]

Description:
The Set-MailboxUser Cmdlet fails when applied to an uninitialized mailbox. This is 100% reproducible.

Steps to reproduce:

1. Create a new Exchange mailbox.
2. Do not initialize the mailbox. This normally happens automatically when opening the mailbox in Outlook or OWA.

Actual results:

1. Set-MailboxUser hangs forever waiting for the mailbox to become available so that it can be reconnected.
2. The mailbox immediately disappears from Exchange and cannot be recovered.

Expected results:

1. Set-MailboxUser should issue a warning that the mailbox is uninitialized and is being skipped.
2. It may be desirable to have an option mode that creates a new mailbox object for the destination user to ensure that all destination users end up with an available mailbox.

Additional info:
If an Exchange mailbox has never been initialized, then disconnecting it results in immediate deletion instead of moving it to the list of Disconnected Mailboxes.