What's an easy to use, preferably open source email program. My father just turned 77, and only answers enails days later, even though I know he watches Youtube every day. My guess is that email has become too cumbersome. I installed Thunderbird for him years ago, but he quickly went back to the Gmail web interface because that was easier, so I'm clearly looking for something much easier than both. (He's on Windows, but with the amount of trouble Windows these days cause even seasoned power users, we might have to change that some day).