I worked at AWS and interviewed SDE candidates, and thus had to enter updates into the system that manages the whole hiring process. They have interview notes g

I worked at AWS and interviewed SDE candidates, and thus had to enter updates into the system that manages the whole hiring process. They have interview notes going back to the company's founding. (FWIW, we could only view prior notes on people we were interviewing, the permissions are quite strict.) The recruiters are absolutely using the same system, they have to enter all their contacts with candidates in order for the interviewers to schedule an interview. So if you're getting contacts while you've signed an offer, I'd suspect they're just spamming a list and only checking the system if people bite.