Which Exchange cmdlet shows who has access to a particular user's mailbox and what type of access they have?

Which Exchange cmdlet shows who has access to a particular user's mailbox and what type of access they have?

• Look-MailboxPermission -Identity username
• Open-MailboxPermission -Identity username
• Get-MailboxPermission -Identity username
• View-MailboxPermission -Identity username 

EXPLANATION

​This question seems to get asked a lot, and people are unaware how easy the answer really is. Here it is:

• 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 Send As 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)