Geary: New lightweight email reader for GNOME designed around conversations
yorba.org
yorba.org
Shotwell and Geary are both written in Vala, a C#-like language layered on top of the GObject system. It will be interesting to see how Vala matures. It has always seemed like a messy abstraction, building it upon GObject, rather than its own type system.
If you develop in C#, Java, Python, or Ruby then you need a layer between GTK and your language which can make their type systems work together. But Vala was designed around the existing GObject system, and since it compiled directly to C it didn't need much in the way of a glue layer, at least for GObject-based libraries.
In fact, Jurg, the creator of Vala agrees on that enough that he created Dova: https://live.gnome.org/Dova it's no longer actively maintained, but it stands to illustrate the point.
I don't see the point of discussing a mail client that doesn't have fast full-text search that scales to a million messages. If it wasn't designed in from the beginning, why should we have any confidence that it will actually work, when so many still fail to deliver? I use Gmail and Notmuch, both of which I think are best in class, yet are still only barely fast enough.
2. Does it support S/MIME or PGP?
3. Can I configure it to view and respond only in plaintext?
3a. When not in plaintext mode, what this guy asked: https://news.ycombinator.com/item?id=4974983
Vala resembles C# most closely. It preprocesses down to C, and gives you a great API to the GObject C object system, and in particular gives you good access to glib, including its string, list, etc. libraries. It also is intended to give you reasonable access native C libraries (optimized for those that follow the GObject conventions, but not restricted to those) and has a much richer type system than C.
I'm not particularly sure there exists a language where you can say that you can't exploit stack overflows, but it's probably much harder than in your average C application and on par with C#, Objective-C, Java, Python, etc.