With fastmail you can just make a alias. My address is me@mydomain.com and in the settings you can make a alias where you can just use something like garbage@mydomain.com
For example, my Twitter address might be twitter@mydomain.com, my Google address google@mydomain.com and so on. All of those go straight to my inbox unless I decide to set up individual filters for them.
The downside is that I can’t easily migrate to a service that doesn’t support this.