I was very sceptic for a long time. Then, I slowly started to trust the kmail2/akonadi combination. I've been using it on my office desktop for a long time, and it works well and is very stable and fast there. (Might be related to the fact that the IMAP server is just across the lawn.) Some time ago, when I deemed things solid enough I even upgraded my laptop again, despite earlier problems. In Gentoo, we've been keeping kdepim-4.4 around all the time, and as you may have read, internal discussions led indeed to the decision to finally drop it some time ago.
What happened in the meantime?
1) One of the more annoying bugs mentioned in my last blog post was fixed with some help from Kevin Kofler. Seems like Debian stumbled into the same issue long ago.
2) I was on vacation. Which was fun, but mostly unrelated to the issue at hand. None of my Gentoo colleagues went ahead with the removal in the meantime. A lot of e-mails accumulated in my account.
3) Coming back, I was on the train with my laptop, sorting the mail. The train was full, the onboard WLAN slightly overstressed, the 4G network just about more reliable. Network comes and goes sometime with a tunnel, no problem. Or so I thought.
4) Half an hour before arriving back home I realized that silently a large part of the e-mails that I had (I though) moved (using kmail2-4.10.3 / akonadi-1.9.2) from one folder to another over ~3 hours had disappeared on one side, and not re-appeared on the other. Restarting kmail2 and akonadi did not help. A quick check of the webmail interface of my provider confirmed that also on the IMAP server the mails were gone in both folders. &%(/&%(&/$/&%$§&/
I wasn't happy. Luckily there were daily server backup snapshots, and after a few days delay I had all the documents back. Nevertheless... Now, I am considering what to do next. (Needless to say, in my opinion we should forget dropping kmail1 in Gentoo for now.) Options...
a) migrate the laptop back to kmail1, which is way more resistant to dropped connections and flaky internet connection - doable but takes a bit of time
b) install OfflineIMAP and Dovecot on the laptop, and let kmail2/akonadi access the localhost Dovecot server - probably the most elegant solution but for the fact that OfflineIMAP seems to have trouble mirroring our Novell Groupwise IMAP server
c) other e-mail client? I've heard good things about trojita...
Summarizing... no idea still how to go ahead, no good solution available. And I actually like the kdepim integration idea, so I'll never be the first one to completely migrate away from it! I am sincerely sorry for the sure fact that this post is disheartening to all the people who put a lot of effort into improving kmail2 and akonadi. It has become a huge lot better. However, I am just getting more and more convinced that the complexity of this combined system is too much to handle and that kmail should never have gone the akonadi way.