Quite a few customers that are using Exchange Online Archiving in an Exchange Hybrid environment, where they have their primary mailboxes on-premises and the archive mailboxes in Exchange Online. This makes a very flexible solution and a perfect start to utilize but not go all in to the cloud.

Just as in a “regular” hybrid environment, you have the possibility to on and offboard the archive mailboxes from and to the on-premises Exchange server. While testing offboarding of an archive mailbox a while ago, I ran in to an interesting error related to the ExchangeGuid attribute.

The exact error message trying to start the moverequest was as follows:

“Multiple objects with Guid 1b2eaa95-0d64-4469-9fb2-d8f9be3e28ce were found”

Multiple objects with the same Guid, could that really be true? Investigating further confirmed the error message. All users in Exchange Online/Office365 had the same value in the ExchangeGuid attribute, even if they didn’t have an archive mailbox.

SOLUTION
The following kb describes a similiar problem in a hybrid environment, but the exact solution could not be applied in my scenario since the RemoteMailbox-cmdlets isn’t working in EOA scenarios. It do however state that in order for a successful move, the ExchangeGuid should be the same on-premises as in the cloud.

After doing the change on one user as below the move started and completed successfully.

#Connect to Exchange Online and Exchange On Premises with prefixes
$cred = Get-Credential
$OnPremSess = New-PSSession -ConfigurationName Microsoft.Exchange `
                            -Authentication Kerberos `
                            -ConnectionUri http://exchangeserver/powershell
$O365Sess = New-PSSession -ConfigurationName Microsoft.Exchange `
                          -Authentication Basic `
                          -ConnectionUri https://outlook.office365.com/powershell-liveid/ `
                          -AllowRedirection:$true `
                          -Credential $cred
Import-PSSession $O365Sess -Prefix Cloud -AllowClobber
Import-PSSession $OnPremSess -Prefix OnPrem -AllowClobber

#Get the On-Premises mailbox
$Mailbox = Get-OnPremMailbox -Identity johan@365lab.net
#Get the Exchange Online MailUser
$MailUser = Get-CloudMailUser -Identity johan@365lab.net
#Change the ExchangeGuid to match the on-premises Guid
$MailUser | Set-CloudMailUser -ExchangeGuid $Mailbox.ExchangeGuid

Since it worked on one user, I then decided to to the change on all users that had EOA activated, as below:

#Get all Mailboxes with EOA Activated
$Mailboxes = Get-OnPremMailbox -Filter {(Archivestate -eq "HostedProvisioned")}
foreach ($Mailbox in $Mailboxes) {
    $CloudUser = Get-CloudMailUser -Identity $mailbox.userprincipalname
    if ($CloudUser.ExchangeGuid -ne $mailbox.ExchangeGuid) {
        $clouduser | Set-CloudMailUser -ExchangeGuid $mailbox.ExchangeGuid
    }
}

I still have a MS support case open regarding how the attribute ended up the same on all users and will update the post when we have identified the root cause.

Let me know if you have questions!

/Johan