It should be an opensource project that people can run themselves on node or linux or whatever. They are logging in via Oauth, pulling all emails from gmail, scanning them for some keywords/patterns and then submitting removal requests to those services. It be perfect for a standalone opensource project, all someone needs to run it is their google oauth key from developer dashboard.
Otherwise we have to trust "someone" whoever it is that designed this service to not keep all the emails they pulled out of your account for processing for whatever nefarious purposes one can imagine.
I mean if I ever wanted to mass harvest peoples inboxes then this is exactly how I would approach it and hope most people just click "next" > "next" on the permissions warning that google shows, which most people would.
Otherwise we have to trust "someone" whoever it is that designed this service to not keep all the emails they pulled out of your account for processing for whatever nefarious purposes one can imagine.
I mean if I ever wanted to mass harvest peoples inboxes then this is exactly how I would approach it and hope most people just click "next" > "next" on the permissions warning that google shows, which most people would.