On Linux, you'll find a cornucopia of email clients, most of which are open-source and can be found in the standard repositories. The open-source clients are typically all you need to get the job done ...

Wine translates Windows system calls to make apps run on Linux, and is supported by a broad community. Bottles organizeWwine ...

I've used a lot of note-taking apps over the years, but Trilium has reset the bar for what I expect in such tools.