Recently, a German solution has been working for me, while the Ronny link, unfortunately, does not work, since I just do not get any answers from the server: https://www.nico-beuermann.de/blogging/archives/115 -Zugriff-auf-iCloud-Kalender-mit-Thunderbird.html
You will need three ingredients for Thunderbird:
a. your calendar server (especially the xx number in pxx-caldav.icloud.com)
b. your user id ( dsid )
with. calendar id ( guid )
In short (and in English):
- Logging into your iCloud calendar in your browser is the first important step.
You can use Firefox or Chrome to browse the web; I will continue to use Chrome for this explanation.
Press Ctrl + Shift + I and go to the Network tab; it may be empty, because recording may also begin after pressing Ctrl + Shift + I; if it is empty, just restart access to the open network tab.
In my case, it was useful to right-click on a column to additionally show the domain
checking a domain or just hanging on links, you can find xx in pxx, this is your specific server; the rest of the domain does not matter ( information a )
Then I clicked on one entry with the domain pxx-calendarws.icloud.com
in a new new window, you can click the title and find dsid somewhere below in the query string parameters; alternatively, you can find it in the url; dsid matches your user ID ( information b )
now switch from “Headers” to “Disclaimer”; you may need to check multiple url strings to find them with the correct answer, but you will find several guid entries that match your calendar IDs ( info c )
Now you have all three pieces of information. In Thunderbird with the Calendar Lightning plugin, now add a network calendar like “CalDAV” (iCalendar will not work!). There you can enter the following URL with the information in bold:
https: // p xx -caldav.icloud.com/ DSID / calendars / reference
Et voìla. You will need to enter your credentials for iCloud. This worked on the date of this post with Thunderbird 45.8.0 with Lightning 4.7.8.
July 18, 2017 Patch: Apparently, sometime in June, Apple changed something with the system. Now you need to activate two-factor authentication to create application-specific passwords. You can do this using any of your Apple devices. You must then log in to your Apple account. In the security area, you can generate a password. Use this to log in to your thunderbird with your email address. This seems to be normal.
Without two-factor authentication, you cannot activate application passwords. And without an application-specific password, CalDAV seems to be no longer available.
Update September 5, 2017 . PGuid seems to work sometimes, but guid is not for the calendar id. So take care.