Mention everyone in a Teams Chat.

I have created a Power App which users can request permission to carry out work. I have set up an action on the Submit button to email the system owners for permission, however, I would also like to set up a message in the relevant Team Channel, but mention (at) everyone.

I have the following code - - which allows me to mention myself but cannot fo the life in me figure out how to get the whole channel team mentioned.

MicrosoftTeams.PostMessageToChannelV3("821cb984-6025-4c6a-a637-e1d65ea580e2","19%3A6mlQMhqLXUCF-6zkKd9Gg833WWD65zQfAZUVMm6Kp5Y1%40thread.tacv2",{content: " <at>joe.bloggs@company.com</at> MessageBody.",
        contentType: "html"})
 
On the Teams channel there is an option to get the Channel email address but that hasn't worked unfortunatly.