Removing Hype of Email Clients

Over the decades I have used many Email clients, starting in the early 90's with "text based" ones in a pure SCO Xenix/Unix environment.
At the office I have used Novell Groupwise, MS Outlook as well as Lotus Notes, whilst at home its Eudora and Thunderbird that I have used extensively. Over the years I have tested many more, some were truly terrible.
Why something so simple as an email client still causes so many a user "distress", is still a mystery to me. We put a man on a moon in 1969, yet still can't seem to get a truly great email client.

In the work environment, the Lotus Notes client was the most unintuitive and painful interface I ever used. Whilst the Lotus Domino server was very robust (more so than MS Exchange in my experience), it was the Lotus client that was its great weakness!
Novell Groupwise was intuitive and easy to use, but somehow never managed to beat the success of Microsoft once Novell's fortune started to decline.
MS Outlook was to be the most popular in global use, but for me, whilst the Outlook client was OK, I cannot say the same for the Exchange server. I found it to be susceptible to corruption and even temperamental at times.

For home use, I was to use Eudora for 20 years before migrating to Mozilla's Thunderbird.
I did mess around with Pegasus for a while, and mention it as it was certainly was one of the better clients that I experimented with. Outlook Express was a total non-starter for me. Not at all robust, thus lacking stability in my opinion!

BUT Eudora (first developed in 1988) was truly the best mail client I can honestly say I ever used. It was always very popular with Power Users (Mac and Windows), this as it was highly customizable & flexible. Sadly Eudora was eventually to be dumped by its owner Qualcomm (in 2006), and without ongoing improvements, began to face compatibility issues, specifically its support for character encoding. To this day I am yet to see an email client that has as much WOW factor as Eudora. Even Apple Co-Founder Steve Wozniak stated in 2009 (to Lifehacker) that be believed that Eudora was the most important productivity tool he had!
Whilst I use Thunderbird daily (I really don't like Browser based email, and prefer to often work off-line), still miss what I consider to have been the best email client EVER!