I have been using KDE for a while, while I like many features I am looking for suggestions to the default email client:
Kmail - completely unusable for me and the only one which could maybe be integrated with kontacts, it could not receive mails from IMAP or pop or would receive only sometimes
Geary - good but too minimal, I need at least some kind of contact list and mailing lists feature, maybe this integrates with gnome contacts? I couldn’t find anything in settings
Aren’t you concerned that the development is in the hands of just one guy?
Not the above poster, but for me: it’s a slight concern but AFAIK the profiles are interchangeable so it’s pretty trivial to just switch back to Thunderbird if anything does happen.