The standard alert functionality to send an alert to all staff doesn’t work like it does with on-premise environments.

There are 4 groups available that you would think would just work :

Except none of them do.  You will get the following error message :

But even though you get an error message, the alert creates anyway, so don’t forget to go and delete it or it will just cause confusion later on.

You need to create an all user mail enabled security group in the Office 365 Admin Panel (Groups) first – AND make sure you change the setting for “allow external senders” to ON.  You can then add that group to the alert / workflow and everything will be fine.  How do you know it’s all cool?  You will get an email confirming that you have successfully created the alert.  No email means something is still wrong.

It’s a cloud thing….