So, to summarize:
- Given a private category with email-in authorized for unknown email addresses (i.e., belonging to no existing account, AKA staged user)
→ if an email comes in from an unknown address: it is delivered to the private category
→ if an email comes in from a known address: it is delivered if and only if the user is a member of a group authorized to access the category.
Therefore, if you want to use email-in for a CFP, configure a private group’s email-in and use that address. Messages can be “made public” and turned into a topic in a category (private or not).