Finishing a migration to Office 365 and want to send the client a list of remaining user mailboxes that need moving (or deleting!).
get-mailbox and get-mailboxstatistics both have their uses, but I really needed to use something that combined them both.
I found the solution at https://www.experts-exchange.com/questions/28399371/Combining-Get-Mail-Get-Mailboxstatistics-To-Pull-UsageLocation-LastLogonTime.html
And adapted it to my own means:
Get-Mailbox -ResultSize Unlimited | sort-object | Select-Object Name, primarysmtpaddress, @{n="Mailbox Size";e = {$MBXstat = Get-MailboxStatistics $_.name; $MBXstat.TotalItemSize}}, @{n="LastLogonTime";e = {$MBXstat = Get-MailboxStatistics $_.name; $MBXstat.LastLogonTime}} | Export-Csv C:\temp\LastLogonTime.csv
This outputs the User name, Primary SMTP Address from get-mailbox and Mailbox size (formatted to MB) and last logon time from get-mailboxstatistics.