Not the author, but this just came up in the Ubuntu app store when I was installing Evolution. From a quick search around the web, it seems like it's gotten some good coverage and, despite appearance, is not electron-based [1]. The second interesting thing is solidly monetized, so may not be as much of a long-term risk to download/install/adapt to. They've also apparently been around for at least a year or more, getting some TC coverage [2], so I though I'd share with the HN folks, after seeing an increased amount of discussion around the difficulty of being in the email space :)
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[1] https://en.wikipedia.org/wiki/Hiri_(email_client)
[2] https://techcrunch.com/2016/06/07/hiri/