From Vasil Michev

source: http://www.michev.info/Blog/Post/77/Quickly-list-all-mailboxes-to-which-a-particular-user-has-access

• List all mailboxes to which a particular user has Full Access permissions:

PS C:\> Get-Mailbox | Get-MailboxPermission -User vasil

Identity             User                 AccessRights

——–             —-                 ————

HuKu                 Vasil Michev         {FullAccess}

retail               Vasil Michev         {FullAccess}

sharednew            Vasil Michev         {FullAccess}

testplan2            Vasil Michev         {FullAccess}

WC                   Vasil Michev         {FullAccess}

• List all shared/user/room/whatever mailboxes to which particular user has Full Access permissions:

PS C:\> Get-Mailbox -RecipientTypeDetails UserMailbox,SharedMailbox -ResultSize Unlimited | Get-MailboxPermission -User vasil

Identity             User                 AccessRights

——–             —-                 ————

HuKu                 Vasil Michev         {FullAccess}

retail               Vasil Michev         {FullAccess}

sharednew            Vasil Michev         {FullAccess}

testplan2            Vasil Michev         {FullAccess}

• List all mailboxes to which members of a particular security group have access:

PS C:\> Get-Mailbox | Get-MailboxPermission -User secgrp

Identity             User                 AccessRights

——–             —-                 ————

Bathroom             secgrp               {FullAccess}

• List all mailboxes to which a user has Send As permissions:

PS C:\> Get-Mailbox | Get-RecipientPermission -Trustee vasil

Identity                            Trustee                             AccessControlType                   AccessRights

——–                            ——-                             —————–                   ————

sharednew                           Vasil Michev                        Allow                               {SendAs}

• List all user mailboxes to which members of a particular security group have access:

PS C:\> Get-Mailbox -RecipientTypeDetails UserMailbox -ResultSize Unlimited | Get-RecipientPermission -Trustee secgrp

Identity                            Trustee                             AccessControlType                   AccessRights

——–                            ——-                             —————–                   ————

HuKu                                secgrp                              Allow                               {SendAs}

•  List all mailboxes to which a particular security principal has Send on behalf of permissions:

PS C:\> Get-Mailbox | ? {$_.GrantSendOnBehalfTo -match “vasil”}

Name                      Alias                ServerName       ProhibitSendQuota

—-                      —–                ———-       —————–

Bathroom                  bathroom             amspr03mb084     49.5 GB (53,150,220,288 bytes)

WC                        WC                   dbxpr03mb096     9.5 GB (10,200,547,328 bytes)

Script to connect to Office 365 and collect the last logged on date/time, mailbox size and item count for each mailbox and archive mailbox for every user within your organization.

The following script was specifically written for a client recently which I thought would be good to share with the wider community. This will connect to Office 365 and collect the last logged on date/time, mailbox size and item count for each mailbox and archive mailbox for every user within your organization.

Those users without an archive mailbox will be returned as ‘No Archive’

For more information about this script please see the source at: https://gallery.technet.microsoft.com/scriptcenter/Find-Mailbox-and-Archive-2859b540

$Office365Credentials = Get-Credential
$session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri "https://ps.outlook.com/powershell/" -Credential $Office365Credentials -Authentication Basic -AllowRedirection
Import-PSSession $session
 
Write-Host "Gathering Stats, Please Wait.."
 
$Mailboxes = Get-Mailbox -ResultSize Unlimited | Select UserPrincipalName, identity, ArchiveStatus
 
$MailboxSizes = @()
 
foreach ($Mailbox in $Mailboxes) {
 
                $ObjProperties = New-Object PSObject
               
                $MailboxStats = Get-MailboxStatistics $Mailbox.UserPrincipalname | Select LastLogonTime, TotalItemSize, ItemCount
               
                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "UserPrincipalName" -Value $Mailbox.UserPrincipalName
                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "Last Logged In" -Value $MailboxStats.LastLogonTime
                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "Mailbox Size" -Value $MailboxStats.TotalItemSize
                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "Mailbox Item Count" -Value $MailboxStats.ItemCount
               
                if ($Mailbox.ArchiveStatus -eq "Active") {
               
                                $ArchiveStats = Get-MailboxStatistics $Mailbox.UserPrincipalname -Archive | Select TotalItemSize, ItemCount
                               
                                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "Archive Size" -Value $ArchiveStats.TotalItemSize
                                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "Archive Item Count" -Value $ArchiveStats.ItemCount
 
                }
                else {
               
                                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "Archive Size" -Value "No Archive"
                                Add-Member -InputObject $ObjProperties -MemberType NoteProperty -Name "Archive Item Count" -Value "No Archive"
                               
                }
               
                $MailboxSizes += $ObjProperties
 
}             
               
$MailboxSizes | Out-GridView -Title "Mailbox and Archive Sizes"
 
Get-PSSession | Remove-PSSession