Office 365 Shared Mailbox Sent Items Copy Feature

By default, emails sent from Shared Mailbox are only saved in the user’s Sent Items folder but ideally, it can be also copied in the Shared Mailbox’s Sent Items folder as well.

To enable this Sent Items Copy feature,

First, connect to Office 365 using:

$userCredential = Get-Credential
$Session = New-PSSession -ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/ -Credential $UserCredential -Authentication Basic -AllowRedirection
Import-PSSession $session 

And then:

Set-Mailbox emailaddress -MessageCopyForSentAsEnabled $true

Fairly easy, and straightforward.