Assuming the version that shipped with each Ubuntu has been different each time, and you'd certainly be hard-pressed to tell at times, that's at least six versions I've tried. And all have sucked.
I'll gloss over the experience of trying Evolution version crap.useless to save myself the anguish. Evolution continues to be so appalling that the future for webmail would look as bright as ever amongst Linux users, even if the general public weren't webmail-mad. Despite competing in a category of applications that's practically defined by its members' lameness, Evolution is so beyond hope that I won't waste any more time or any more breath on it.
If you think I exaggerate, you don't even need to install and try Evolution. You can learn a lot from the Evolution FAQ:
Why cannot I reset word wrap setting for outgoing mails at 72 characters?
Sorry, the value is hardcoded.
Can I change/personalize the "On <date>, <person> wrote:" string when replying?
Currently you can only change this if you compile from source yourself.
In fact, you can probably get a pretty clear picture by just reading one FAQ question's title: "Does a version for Apple(R,TM,C,whatever) Mac OS(R,TM,C,whatever) exist?" There are two other FAQ entries with the same childishness surrounding "Microsoft", "Windows", "Sun", and "Solaris".
I think that tells you all you need to know.
Don't get me wrong: I think having a vision or an ethos is important, and it's a good and wise decision to not add every single feature anyone on the internet can think of. At the same time, I think it's even more important that you communicate the vision. Especially if one of your philosophical decisions has become a FAQ. That's people's way of telling you they don't understand what the hell you're trying to say. (And to be perfectly clear, though this shouldn't need to be said: that's your fault, not theirs.)
According to their web page "Evolution provides integrated mail, addressbook and calendaring functionality to users of the GNOME desktop". That sounds pretty inclusive to me. That says mainstream to me. That says "we are to the GNOME desktop what Mail.app and Outlook are to Mac OS and Windows". Not "we will give smart-arse answers to perfectly reasonable questions".
Somehow, this "fuck you" attitude manages to carry over to the UI, which would be a neat trick if that were actually useful.
There's Thunderbird, too, but that's like Evolution for people who like more knobs and switches. (Plus the handful of people who actually miss the built-in mailer from late 1990s versions of Netscape.)
I wonder how we got here? Once upon a time, not long ago, Unix was the only place you'd find sensible mailers. They were terminal-based, of course. One of them (mutt) even survives, in some of the more beard-overgrown corners of the internet. Various people had already taken us from terminals to GUIs, giving us nicer (and more) fonts, and eventually giving us HTML mail for amazon and netflix and newegg (and spam). But fast full-text search? Good local caching to cope with high latency/low availability connections? Great editors? Nope. We even took a step backwards on that last one, giving up $EDITOR. Not a problem for the mainstream user who doesn't have a favorite editor, but perhaps one reason why the people who might actually write the code have little inclination to do so. "You want me to use Emacs/Vim to write a program, the use of which would mean that I can't use Emacs/Vim as much? Yeah, sure; I'll get right on that."
As regular readers know, I'm neither an Emacs nor a Vim person, but nevertheless it was actually the crappiness of Evolution's editor, and of Mac OS' Mail's editor (in more recent versions; I think they improved HTML editing at the cost of plain text editing) that made it easy to give up both. If I'm going to have a crappy editing experience, I may as well take the browser's crappy editing experience. For one thing, I have to live with editing so many other things in the browser that I may as well learn its quirks. More importantly, unlike most of the Linux desktop, Firefox actually tends to improve as time passes.
I have yet to become a creationist, but I have abandoned Evolution, and I am happily using webmail for all my mail needs; an idea that I would have considered to be one of the direst of heresies in the 1990s.
Problem: no-one who could write one wants a decent desktop mailer for Linux, so there will never be one.