Admins may want teammates using an inbox to only send messages with their own individual channel. This could be because they want a consistent customer experience or in some cases to avoid sending an email to customer A from the email@example.com shared channel.
This is partially solved if teammates are invited with a blank default channel, and then the teammate's individual channel will become their default once it is added. However, this is only a default so still leaves room for a shared channel to be used accidentally, for example, if a teammate changes their default channel preference or their individual channel loses authentication.
How could we allow admins to prevent shared channels being used? Some potential solutions:
Introduce channel access controls, to define which teammates can access a certain channel
Admins can specify whether a channel can be used for outbound messages. This could be an inbox-level setting, and allow admins to select 'Individual channels only'
Prevent users from changing their default channel preference
Allow admins to build customized warnings, that display to users if they try to send an message with the wrong channel