@meissa - Thanks for your input. I used Thunderbird extensively in the past (a long time ago now) but I wasn't aware of the CardBook add-on. DAVx5 I did come across briefly during my research so will check it out some more. I have had a quick play around with Nextcloud (via a cloud hosted provider). Can I ask - for your Nextcloud backend, do you host this on your own web server or perhaps self-host this on a local network which can be accessed remotely?