had a bank spend an hour making phone calls before letting me use bankname@mydomain.com one time, they ended up letting me use it in the end but acted like i was hacking the entire bank it was really amusing.

This scheme has been invaluable for spending decades on the internet. When a company sells your email off you instantly know who sold it and blocking that address on your end fixes the issue immediately.

Anyone who wants to try a lightweight version of this google supports +tokens in the name portion of your email address. So if you are steve@gmail.com and you sign up at nike.com enter the address as steve+nike@gmail.com (if their system lets you, many do not). then if you get spam at steve+nike@gmail.com that isn’t from nike you know it was them who sold your address.

makes filtering easier too like if you fish sign up as steve+fishing at all your fishing sites and you can catch them all with one fiter and don’t have to add each domain individually to have them labeled properly.