ever wanted to export a list of all your Microsoft Exchange mailboxes and also the delegates of the shared mailboxes. The following PowerShell will export the list to c:\temp folder to a file named sharedmailboxes.csv
Get-Mailbox -RecipientTypeDetails SharedMailbox -ResultSize:Unlimited | Get-MailboxPermission |Select-Object Identity,User,AccessRights | Where-Object {($_.user -like '*@*')}|Export-Csv C:\Temp\sharedmailboxes.csv -NoTypeInformation