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 smb@contoso.com -MessageCopyForSendOnBehalfEnabled $True
Set-Mailbox smb@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 smb@contoso.com -User user1@contoso.com -AccessRights FullAccess -InheritanceType All
Add-MailboxPermission -Identity smb@contoso.com -User user2@contoso.com -AccessRights FullAccess -InheritanceType All
Add-RecipientPermission -Identity smb@contoso.com -Trustee user1@contoso.com -AccessRights SendAs
Add-RecipientPermission -Identity smb@contoso.com -Trustee user2@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