I do the exact same thing.
It gives you quite a bit of insight and control.
some examples:
- at some point my email for amazon was shared, and I started getting offers from some vendor to 5-star review one of their products on amazon. I changed my amazon email address. (I generally trust amazon)
- emails from my bank have to go to a specific email address. I can be pretty certain it is my bank contacting me.
- I generally do not give my email address to retail stores. On several occasions I've given it to them for deliveries, telling them it isn't for anything but for the delivery. I'd say 80% of stores are super disrespectful of this. One spammed me every. single. day. with offers, until I got the delivery and turned off that email address.
- I once gave out a specific email address to a friend. He shared it with a second person to coordinate all of us meeting. and then I started getting phished so we figured out that the second person had his email compromised.
- I rented a car from hertz and had to give an email address. and then they sold it to other companies.
- linkedin stuff. easy to spot fakes since they don't go to my linkedin email address. Also easy to spot emails from people contacting me who got the email from linkedin.
It goes on and on. More people should do this.