I have a second alias domain configured in o365 for the same primary domain.
So, I put a mailbox on plesk for the address I need, turned on auto-forward to the recipient@aliasdomain which isn't on plesk and it ends up in the correct mailbox.
More steps than should be necessary though. +1 for native support of SMTP send-only use case
WORKAROUND:
I have a second alias domain configured in o365 for the same primary domain.
So, I put a mailbox on plesk for the address I need, turned on auto-forward to the recipient@aliasdomain which isn't on plesk and it ends up in the correct mailbox.
More steps than should be necessary though. +1 for native support of SMTP send-only use case