After more than ten years, today I finally said goodbye to KMail (and eventually to the whole KDE-PIM package).
I started working on the italian translations of the KDE-PIM programs many years ago, that was my first contribute to the open source software (before I became a professional developer) and of course KDE and the PIM package were my beloved choice for every-day email and addressbook/calendar activities.
The pain started when KDE4 introduced akonadi and all the DB-backed stuff (virtuoso and its companions), let aside the endless configuration and installation problems, kmail it’s now completely unusable: for example I couldn’t make filters work anymore and it suddenly started asking for account’s passwords at reandom.
I’m a bit sad about leaving KMail, it has been a good pal and I liked its rich features and nice UI.
Goodbye KMail, it’s a real pity that KDE it’s slowly committing suicide.
BTW switching to thunderbird was not straight, consider using the utility described in the following link to convert your email folders: Migrating from KMail to Thunderbird