我尝试编写以下代码来检查Outlook日历权限：

$Usermailbox = Read-Host "Please enter the mailbox whose permissions you want to see"
      Get-MailboxFolderPermission -Identity "$Usermailbox :\calendar"

但当我试图这样做时，我得到了一个错误

Get-MailboxFolderPermission: xxxx|Microsoft.Exchange.Configuration.Tasks.ManagementObjectNotFoundExceptio
n|The specified mailbox Identity:“xxx ” doesn’t exist.

我知道这是因为代码可能将$Usermailbox：\Calendar视为一个字符串
如何将它们分开？