You can click on the email address in question and adjust its channel:
https://admin-docs.zammad.org/en/latest/channels/email/accounts/secondary-addresses.html
This has no negative effect incoming wise and will use the configured channel for outgoing. Just make sure that this is allowed email wise (DNS configuration etc…). Also note that re-authentication Microsoft 365 channels might revert this change - I am not sure about that regard.
