"Email in allowed groups" setting is too permissive

[Lilly]

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Configure incoming email to create new topics or group messages

If you have already set up reply via email, or you are on a hosting plan that pre-configures your incoming email, you’re now ready to set up Starting a New Topic via Email. Site Settings The incoming emails feature is globally controlled by these 3 site settings: email_in: this is the only setting that must be enabled for incoming emails to work. email in allowed groups: a user must belong to this group in order to send an email to Discourse. enable_staged_users: create staged users for unkno…