Hello, I run a. Thunderbird v 78.14.0 (64-bit) on a Macbook Pro 13"mid 2012 with Mac OS 10.10.5 (Yosemite) b. Thunderbird v 115.5.1 (64-bit) on a Macbook Pro 15" mid 2012 with macOS 10.15.7 (Catalina) How do I make happen, that I sync the calendars in both Thunderbirds constantly, i.o.w. instantly (like for example the iMAP emails do)?? I find the option for new calendars: "On the network" ... Which network is here meant??? In the help there is not much info about it. I am not using and will not use Google or any kind of "social media" (!) Can I use my own homepage host (which has some webspace left) in order to sync? Or for example an online storage like mega.nz ? Or could the both macs just sync the thunderbird calendars just via WiFi/WLAN directly (AirDrop ?) or via Bluetooth ?? It would be so great if calendar sync would be as easy as the emails do! Thanks for you advice! Best wishes, Thomas