Hi forum,

I am trying to stop Outlook from AutoMapping shared mailboxes.

Once connected via Powershell I am attempting to run the following commands, extracted from https://technet.microsoft.com/en-us/library/hh529943

$FixAutoMapping = Get-MailboxPermission sharedmailbox |where {$_.AccessRights -eq "FullAccess" -and $_.IsInherited -eq $false}
$FixAutoMapping | Remove-MailboxPermission
$FixAutoMapping | ForEach {Add-MailboxPermission -Identity $_.Identity -User $_.User -AccessRights:FullAccess -AutoMapping $false} 

The first command seems to apply successfully, but fails on the second one 

Are these the right commands to be running on Office 365?

Hi,

As far as I know, to remove automapping for a shared mailbox in Office 365, you should first remove full access permissions for the user from the mailbox by runing the following command:

Remove-MailboxPermission -Identity <Mailbox ID1> -User <Mailbox ID2> -AccessRights FullAccess

Then grant full access permissions back to the user for the mailbox, but don't enable automapping by runing the following command:

Add-MailboxPermission -Identity <Mailbox ID1> -User <Mailbox ID2>-AccessRights FullAccess -AutoMapping:$false

For more details, please refer to this KB article: https://support.microsoft.com/en-us/kb/2646504

Also, this is the forum to discuss questions and feedback for Microsoft Office client. For Exchange Online related question, I would suggest you post in the dedicated forum of Microsoft Online: Exchange Online:

https://social.technet.microsoft.com/Forums/msonline/en-US/home?forum=onlineservicesexchange

The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thank you for your understanding.

Regards,

Ethan Hua
TechNet Community Support

Is there a procedure to do this en mass for a shared mailbox? is it as easy as just adding more users to the command?

emove-MailboxPermission -Identity <Mailbox ID1> -User <Mailbox ID2> <Mailbox ID3> -AccessRights FullAccess

Hi,

I have never tried this before, and don't have an environment to give it try at moment.

I would suggest you go ahead to give it shot or as mentioned above, post in our dedicated forum of Microsoft Online: Exchange Online for further assistance.

Thanks for your understanding.

Regards,

Ethan Hua
TechNet Community Support

If you want to remove all of the automapping settings on a mailbox (or all mailboxes in your environment), you can do so with the -clearautomapping switch on the remove-mailboxpermission cmdlet in Exchange Online (and only Exchange Online. Onprem does not have access to this switch). More about it on my blog:

https://acbrownit.wordpress.com/2015/08/26/clearing-mailbox-automapping-in-exchange-online/