Whenever administrator delegate to user to access multiple shared and resources mailbox with full access permission, they might facing slow performance issue in his outlook during starting up or quit the outlook.

For example user (Jobstreet) complained on the above scenario, the user doesn’t want to auto mapping in his outlook all those Mailboxes although the full permission have been granted earlier. If the users wish to select particular mailboxes, they can manually mapping in their outlook.

Here is the steps to how disabled auto mapping.

Step 1: Connect Exchange Online using windows Powershell.
1.$s = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell -Credential $cred –
Authentication Basic –AllowRedirection

Type your Office365 Global admin gredential

1.$importresults = Import-PSSession $s

Step 2 : Remove the delegation existing Shared Mailboxes or calendar if, any.
1.Remove-MailboxPermission -Identity klmeetingroom1@jobstreet.com -User stevenho@seekasia.com -AccessRights FullAccess

Step 3: Grant permission again with Automapping Parameter.
1.Add-MailboxPermission -Identity klmeetingroom1@jobstreet.com -User stevenho@seekasia.com
-AccessRights FullAccess -AutoMapping:$false

Step 4: Open users Outlook and point cursor to shared mailbox folder Righ click and Disconnect the Mailbox.