Great, here comes the task of setting up SMTP e-mail relays, unless... will Orchestrator work directly with O365 using just the Send Email Activity?
It turns out it does and really simply too.
On the Send Email activity properties, fill out the information on the Details tab.
N.B. Make sure you untick the Task fails if an attachment is missing option if you're not putting an attachment on the mail.
On the Advanced tab enter the email username and password for the account you created in Office 365 that will be used for sending e-mail from Orchestrator.
You can leave the Domain field blank
Logon to Office 365/OWA as the Orchestrator e-mail account, click on the Options button and then About.
Make a note of the Server name and Port as highlighted in the screen shot below (pod51016.outlook.com in this example)
Enter this information into the Connect tab, along with the e-mail account you've setup for Orchestrator to send from
Make sure the Enable SSL option is ticked, otherwise you will get an error in Orchestrator informing you that the SMTP server requires a secure connection.
Check your Runbook in and give it a test run.
If it's setup correctly then this time you should see it succeed.
And voilà, you should end up with e-mails being sent to/from Office 365 without the need for any on-premise Exchange or SMTP relay.
Another, simpler method, is to use the Exchange User Integration Pack.
With this IP installed, you can configure the server to use (again the details from OWA) along with the e-mail and password by going to the Options menu and choosing Exchange User.
Then drag a Create and Send E-Mail activity to your runbook and provide at least the e-mail address to send a mail to, the subject and the body. Other options are available such as priority and attachments via the Optional Properties... button.
Again, another successful e-mail can now be sent.