If someone tries to highjack a ticket by e.g. guessing the ticket no. the e-mail will be logged in the ticket as “public”. This looks a bit weird from customer perspective.
It would be great if default would be set to “internal” or if this behaviour could be set through the admin interface.
To make sure no valid inquiry from someone in the mailchain gets “ignored” that way this function must allow messages to be logged as public if the sender has been mentioned in the mail chain before on TO: or CC:.