Dear Computer Lady,
You have often recommended Thunderbird as an email client–I agree that it’s an excellent program and used to use it myself.
However, few years ago I switched to using Gmail as a client. It can be set up to retrieve mail from multiple providers, has close to unlimited storage space, is very unlikely to disappear, and best of all, it allows you to get mail from anywhere in the world as long as you have an internet connection. It also has excellent spam filtering, and has all the features you would expect from any modern email client. Of course, you also get a free gmail account in addition to any other existing accounts you may have.