Like the questioner, I want an email client, not a webmail service. This is partly, but not entirely, because I am often in situations where I can't get internet access. I used Outlook for years, but eventually changed to Thunderbird because it was better and open source. But when development stopped on it and there was no realistic hope that bugs would be fixed, I went shopping. After some false starts, I eventually settled on eM Client. It's kind of like Thunderbird, but better. It is not open source. It is not free. It is not perfect. But I decided that for a primary tool, I wanted something that would be fixed regularly by people working for a salary. The folks at eM Client actually listen to feature requests, although they don't always implement everything you ask for. I think there are several other similar commercial email products that would probably work as well. I like eM Client, but am not claiming it is better than other products I haven't tried. The email client as a category is fading away because many young people use GMail or some other webmail program. Fortunately there are a few decent email clients remaining for use old folks.

In constructing a language easily learnable by the most people, you'd want to leverage as much existing knowledge as possible. Rather than starting from scratch, it would be more efficient to revise and regularize a popular existing language so that its speakers could adapt and new users could learn easily. The two obvious candidate languages are English and Spanish. Chinese and Arabic are ruled out by the difficulty of learning. The argument for English is that it is the largest language for first and second use and is a popular foreign language for students. The argument for Spanish is that it has more regular spelling and grammar and is easier to learn. If you chose English, you would want to regularize its grammar and spelling while attempting to retain as much vocabulary as possible and bring in useful new words from other languages. Fortunately these changes are already happening through evolution. It’s possible to imagine an official regularization authorized by English-speaking governments and performed by scholars, but the required political steps are unlikely. We’re probably stuck with evolution, which is not all bad.