@daniel
@rl_dane

#KDE has long had a technology called #KParts. Basically you can set up something (including a full app) as a #KPart component and use it elsewhere as part of another (tools bars and menus will merge).

My understanding is that #Kate & #KWrite are a good example. Both now use the same editor component, but Kate adds a LOT of extra functionality to it. The #KDEPIM suite uses the same trick with it's components - they can run separately or as one combined app (#Kontact).

I'm not fully across the technology, so if any experts wish to correct me, feel free.

@eliasp

@rl_dane
You probably want #Kontact. You can set up the *DAVs in the #KOrganiser & #KAddressBook components. Note I run #Nextcloud, and #KOrganiser will add both the #CalDAV & #CardDAV at the same time to both apps. These apps can be run separately, or seamlessly as part of #Kontact - up to you.

It will handle the multiple accounts easily (I currently have four), but only two identities.

@eliasp

@rl_dane
I've been using #KMail for years, but as part of the larger #Kontact app (which gives you Outlook like functionality (contacts, calendar & more)). The interface has not changed over the years.
The idea of identities been different to the accounts allows you to (for example) separate work and personal. For example with each identity you can set up a different signature, and which email address / SMTP server it uses. However the setup for this does need work and is initially confusing for new users.
Note I recently tried #Thunderbird and hated it - I use keyboard short-cuts and TB's were browser-based and not email based (eg CTRL-R / CTRL-U for mark read / unread). I found no way of changing them while being #KDE, that is always an option in #Kmail.

@lunkki #Tuta-tili on nyt luotu. Uutta sähköpostia en tosin olisi tarvinnut, oma osoitteeni on ollut jo parikymmentä vuotta webhotellissa (joka on pariin kertaan vaihtunut).

Tuta tarjoaa sovelluksen #Android'iin ja jonkinlaisen (#AppImage'na pyörivän) myös #Linux'iin. Jälkimmäinen arveluttaa, mutta kokeillaan. Kytkemisestä käytössä oleviin ohjelmiin (#KMail, #Kontact tai vaikka #Vivaldi) ei ilmeisesti kannata uneksia.