Following up on this thread, in case it's useful for someone, here's info on how I ended up migrating my email from Yahoo to a paid service, in three steps.
First, I needed to own a domain.
Luckily I had bought a domain long ago, when good names were not taken yet. Today buying a name is easier than it was back then. For the sake of illustration, let's call the domain mylastname.net. My email address is now the equivalent of
myfirstname@mylastname.net, which is nice and short, and best of all my millennial kids don't mock it the way they did my old yahoo address.
To maintain the ownership of my domain name, I am using Network Solutions, which I don't recommend because they send me annoying sales pitches. I hope their spam doesn't cause me to ignore an important messsage to renew my domain ownership.
Second, I needed a hosting company.
I settled on
Rackspace.com, after first trying out protonmail.com. Rackspace seems to be used by serious tech companies to run their businesses, so it's surely good enough to host my little family email account. I abandoned protonmail because its attention to security is so extreme as to be a nuisance, with its inability to work with applemail on my iphone and ipad, and its need for a tricky "bridge" on a desktop computer.
I am paying Rackspace $10 per month for up to five email addresses. That's enough for my family. Unlike yahoo and other providers of free email, Rackspace explicitly promises not to read my email and sell info about me, and that's what's most important to me. Each address is entitled to 25 GB of email storage, which is a bit more than with a free gmail account.
Third, I needed to set up both my new hosting account and my old mail apps.
This part of the migration was the trickiest, and it was harder than getting started with a free gmail account, but Rackspace provides helpful instructions. Rackspace also offers 24/7 customer service that I didn't need.
The final result is that I now get all my email, as before, through the familiar applemail app on my mobile devices and through the familiar mail app on my desktop mac. I was able to move all my email easily from Yahoo to a protonmail or rackspace account by just dragging the messages from one folder to another in my desktop mail app. To make the last step practical, I first deleted about 20,000 useless email messages from my yahoo account, and that was the most time-consuming part of the whole project.
It's great that I can now keep my same email address when I move from one provider to another. That's an advantage over a free email account, along with the assurance of privacy. However, the paid email providers try to keep you from moving by now offering cloud-based "office" software and storage. Rackspace offers such a cloud service, as does Google's better known gsuite. I'm avoiding those services, and just sticking with simple email hosting, so that I can move my email again easily.