Buying your own domain.
You can then use whatever provider, or host your email service... but at least you don't need to change addresses when switching anymore.
Just make sure your domain registrar is renewable from an alternate email in case shit hits the fan you don’t want to be locked out if something interrupts the service and bow your email doesn’t work and you can’t verify who you are… because… your email doesn’t work.
Select who you are setting up your email with (plenty of different providers, Zoho has a basic free plan that would be suitable for a single domain and only a few users at most; Google, outlook etc. also sell services for custom domains)
Configure the DNS records for your domain to whatever your chosen email provider says (MX records to point to the mail server and some records for DMARC & DKIM to prevent your email being spoofed)
Test it all works and start using it
I'm not going to write a full tutorial so if it sounds interesting I suggest you do more research. The email hosting is typically focused at businesses as they are most likely to be wanting to host email on a custom domain.
I started doing this, maybe 15 years ago, but if I look through my spam folder now, most of it is to the email address I used before I began using unique addresses (the rest is to random addresses in my domains that I've never used).
My hypotheses from that are that
there is probably less 'selling of email lists' going on than we think
I'm less interested in dubious internet sites than I used to be
or (most likely) these days, your internet thing has to be offering me some real value if I'm going to consciously give you any of my data.
MXRoute is what I use as my domain's email server and it's good enough. The included browser email clients (it offers multiple) are sort of trash but if you just use your own it's perfect. It's pretty cheap too
If your mail server supports aliases, you can make one for each site you sign up for. Then if you start getting a bunch of spam, you can delete the alias and you will know which site sold your information.
Yes and no... say if you gave the email address [email protected] when signin up and you start receiving garbage on it, you just delete the alias and move on.
The trick is that you can have several aliases go into the same inbox so you only have to check one place, but each thing is given its own IP making it easier to identify and filter culprits.
You know not to trust that site with any more information. Once the alias is deleted, anything sent to it will result in a delivery failure and you won't get any more spam from anyone they sold that address to.