Hi @AWoody,
This story is at my expense, so pull up a chair, Schadenfreude fans...
By default, every active user email within Workfront will be converted to Adobe Admin Console...which in my case, unfortunately, included dozens of people who'd "popped in" over the years (Workfront support team members, former employees who'd not been deactivated, etc.)...and it was one of the latter who kindly brought it to my attention (and embarrassment). I quickly DELETED all those uses from Adobe Admin Console, used our Excel Updater to add _FakeAddress_ to every such email (thereby avoiding the auto alerts going anywhere...again...) and reran, quietly. In a more orderly fashion, I now gradually convert the handful of users who do in fact need access from _FakeAddress_ to their desired address...which in some cases, isn't what I'd had from back in the day, anyway.
Your mileage may vary. Good luck.
Regards,
Doug