Can I find out how many items are in my public folders?
In order to determine the number of mail, calendar and contact items that are in your public folders, you'll need to run the following PowerShell script.
# Exchange Management Shell Script
# This script can be run to count the number
# of items that exist in all public folders starting
# at the root.
# Set the execution policy
Set-ExecutionPolicy Unrestricted -Force
# Retrieve the credentials
$LiveCred = Get-Credential
# Create and import the PowerShell session for ExchangeOnline
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://ps.outlook.com/powershell/ -Credential $LiveCred -Authentication Basic -AllowRedirection
# Recursively go through all public folders counting the items
Get-PublicFolder -Recurse | Get-PublicFolderItemStatistics | Group-Object -Property ItemType -NoElement
# End Script
This will generate output giving the count and item name (IPM.Note for mail, IPM.Contact for contacts, and IPM.Appointment for calendar items).