For non-smsd emails or a mix of smsd and bubbler emails, you can create a Google Group and then email that group from Outlook.
To Create Google Groups:
In Google, go to the Waffle and select Groups.
Choose Create Group.
Name your group (make sure to make it specific for your group), add members and group manager.
Add Privacy Settings:
More about the roles:
You can edit your members:
Now anyone can email firstname.lastname@example.org and it will go to the people on the list. The manager or owner of the list will need to keep it updated as people start/end with ESS.