These days almost every website asks for a sign-up and if you notice, even the fancy cafes and other shops ask for your email. We don't really know what happens with our email ids. There is a possibility that these websites or shops are forwarding them to other people without our consent. This also leads to a lot of spams, making it hard to keep our inbox clean. However, there is a hack to fix these problems.
One way is to use Temp mail where signing-up for websites is mandatory and you only need to visit those websites once or twice. Temp Mail is a throw-away email service that provides temporary, free, and disposable email addresses. So you could just use it to sign in to any website and forget about the mail-id once you are done using it. This will help you keep your inbox clean and safe from these spammy websites.
Now, what if the website requires you to verify your email, or what if you need to fill in your mail id at some random shop, restaurant, company, etc. Well, in that case, you could use a Gmail trick to tackle these issues. The next time you give your email id to any of these places, use a mutated form of your email-id instead of your usual one. Gmail lets you add a '+' symbol to your first half of the email-id. For e.g, if your mail id is "email@example.com", then you can use something like "firstname.lastname@example.org". The best part of this that you will still get the mail to your usual mail-id and this way you practically have an infinite number of email addresses. You could use this trick for a lot of things. It helps you track who is forwarding your email id without your consent. And in case, there is a chain of a certain company like Starbucks or something location-specific then you can use full stops as well. It can be something like "email@example.com@gmail.com".
You can use email filters to automatically delete these spam emails or organize your emails better. The way to do it is to search for 'deliveredto: "firstname.lastname@example.org"' while setting up a filter on Gmail.