Then I have no idea where the machine is grabbing their email address from in the first place, that option personalizes the email option and populates scan to home.
You stated you already checked the default from information which are these 2.
And since email isn't supposed to be using their information then there is no reason SMTP would be set to use the logged in users credentials here
I have 7 of these devices and none do what yours is doing, every single one is on the 101 release (There truly is at this moment only a single 101 build, there are no spar versions (yet))