CalDAV
Windows 10 supports CalDAV/CardDAV but limits provider-support
Windows 10 supports syncing email, contacts, and calendars with all major providers. However, Microsoft chooses to close it down to a handful of providers.
CalDAV
CalDAV
How to add CalDAV and CardDAV accounts and sync with Windows 10
Set up syncing with your CalDAV and CardDAV accounts with the built-in Windows Calendar and Contacts apps. Windows can sync with any CalDAV/CardDAV server.
CalDAV
Windows 10’s “Interesting Calendars” feature is powered by webcal/iCal
New Windows Calendar feature is just standard webcal subscriptions but interestingly you can’t add your own webcals.
CalDAV
How to add an iCal/webcal calendar to the Calendar app in Windows 10
Learn how to work-around Windows 10 limitations to add iCal and webcal calendars to the Windows Calendar app through Outlook.com.
CalDAV
Synchronize GNOME and all its apps with a CalDAV server
How to set up sync of your CalDAV and CardDAV accounts with GNOME apps like Evolution, Calendar, Contacts, dash-search, and more.
DNS
DNS SRV records usage for email and calendar service discovery
A quick survey of the use of DNS SRV records for auto-configuration of email and calendar hosting services. Provider support is fairly good.
How to install and configure Horde 5 webmail on Debian/Ubuntu
Step-by-step instructions for setting up the Horde webmail and application suite on Linux.