How to find inactive Exchange mailboxes using PowerShell

Inactive mailboxes consume your oraganization's storage resources and create security risks when employees leave or test accounts are deserted. These abandoned mailboxes can complicate compliance audits and increase operational costs. This article covers three methods to identify inactive mailboxes using the Exchange admin center, PowerShell scripts, and specialized Exchange reporting tools like ManageEngine Exchange Reporter Plus.

Method 1: Find inactive Exchange mailboxes using the Exchange admin center

Prerequisite

Before using the Exchange admin center, ensure the account you use to log in is a member of one of these role groups: Organization Management, Recipient Management, or View-Only Organization Management.

Using the Exchange admin center to find inactive mailboxes

You can find inactive mailboxes indirectly through the Exchange admin center using the web interface.

1. Open your web browser and navigate to https://servername/ecp (here, replace servername with your Exchange Server name).
2. Sign in using your Exchange admin account.
3. Navigate to Recipients > Mailboxes.
4. Select the mailbox you want to check from the list.
5. Click the Edit icon (pencil symbol) to open the mailbox properties.
6. In the mailbox properties window, click mailbox usage in the left navigation pane to view the last login time. This will help you determine whether the mailbox is active or not.

Limitations to consider

This method only allows you to check one mailbox at a time and requires navigating through individual mailbox properties for each mailbox you want to check.

Method 2: Find inactive Exchange mailboxes using PowerShell (Get-MailboxStatistics)

Prerequisites

Before using the Get-MailboxStatistics cmdlet, please verify that the below mentioned prerequisites are satisfied:

1. Exchange Management Shell is installed and accessible on your Exchange Server or management workstation.
2. You have appropriate Exchange Server permissions (the Recipient Management, View-Only Organization Management, or Organization Management role).
3. PowerShell is being run with administrative privileges.

Using the Get-MailboxStatistics command to find inactive Exchange mailboxes

The Get-MailboxStatistics cmdlet is used to return information about a mailbox, such as the size of the mailbox, the number of messages it contains, and the last time it was logged on to. The syntax for it is given below:

The syntax for it is given below:

Get-MailboxStatistics
    [[-StoreMailboxIdentity] <StoreMailboxIdParameter>]
    -Database <DatabaseIdParameter>
    [-CopyOnServer <ServerIdParameter>]
    [-DomainController <Fqdn>]
    [-Filter <String>]
    [-IncludeMoveHistory]
    [-IncludeMoveReport]
    [-IncludeQuarantineDetails]
    [-NoADLookup]
 [<CommonParameters>]
                            

Supported parameters

The table given below lists out some of the Get-MailboxStatistics parameters for identifying inactive Exchange mailboxes.

Example use cases using the Get-MailboxStatistics cmdlet

Getting all mailboxes with their last logon time

                               Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Select-Object DisplayName, LastLogonTime
                            

Getting all mailboxes inactive for more than 90 days

                               Get-Mailbox -ResultSize Unlimited | Get-MailboxStatistics | Where-Object { $_.LastLogonTime -lt (Get-Date).AddDays(-90) } | Select DisplayName, LastLogonTime
                            

For this cmdlet, the number inside the AddDays parameter sets the inactivity threshold. For example, -90 checks for mailboxes that haven’t been logged into for the past 90 days. You can change this value to any number you prefer, such as -180 for 180 days.

Method 3: Find inactive Exchange mailboxes using Exchange Reporter Plus

You can use Exchange Reporter Plus to identify inactive Exchange mailboxes with ease. The product supports multiple versions of Exchange Server, including Exchange Server 2003, 2007, 2010, 2013, 2016, 2019, and Exchange Server Subscription Edition (SE). The steps to identify inactive mailboxes are provided below.

1. Log in to Exchange Reporter Plus and go to Reports > Exchange Server > Mailboxes and click Inactive Mailboxes by Last Logon Time under Account Status Reports.
2. Select both the required Exchange Organization and the Inactive Period to filter the data.

Stay informed about inactive Exchange mailboxes

Exchange Reporter Plus empowers administrators with comprehensive visibility into mailbox activity patterns across their Exchange environments. This Exchange reporting solution helps Exchange admins identify inactive Exchange mailboxes with detailed, exportable reports.

Important tips