Hi @Glenn Maxwell ,
Welcome to the Microsoft Q&A platform!
Based on your description, your PowerShell commands are correct. To ensure that emails sent by any user from a shared mailbox are stored in the Sent Items of the shared mailbox, you should use the following commands:
Set-Mailbox ******@contoso.com -MessageCopyForSendOnBehalfEnabled $True
Set-Mailbox ******@contoso.com -MessageCopyForSentAsEnabled $True
These commands allow sent messages to be copied to the Sent Items folder of the shared mailbox for both "Send on Behalf" and "Send As" scenarios.
In addition, make sure that both users have the required permissions to send emails from the shared mailbox. You can verify and assign these permissions using the following commands:
Add-MailboxPermission -Identity ******@contoso.com -User ******@contoso.com -AccessRights FullAccess -InheritanceType All
Add-MailboxPermission -Identity ******@contoso.com -User ******@contoso.com -AccessRights FullAccess -InheritanceType All
Add-RecipientPermission -Identity ******@contoso.com -Trustee ******@contoso.com -AccessRights SendAs
Add-RecipientPermission -Identity ******@contoso.com -Trustee ******@contoso.com -AccessRights SendAs
These commands ensure that both users have full access and Send As permissions to the shared mailbox.
Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.
Best,
Jake Zhang