I have Thunderbird 38.3.0 installed from Fedora's repository (# dnf install thunderbird), and my plan is to use it more frequently in the future for my mail. I have one professional email account on Namecheap with my own domain address, one student email account on my university and one general email account on Gmail. The point with using Thunderbird would be to unify these three accounts into one program to make it more manageable.

One critical step for this to work is to get CardDAV integration in Thunderbird. I'm running a DigitalOcean VPS with CentOS 7 where I have ownCloud installed, which I'm using for syncing files to my computers and my phone. However, I'm also using ownCloud as a CardDAV and CalDAV server for storing and syncing my contacts and scheduled calendar events.

On hover.com I found a very good and short guide (backed up to [1] and [2]) for how to get CalDAV and CardDAV synchronization through the Thunderbird extensions Lightning and SOGo Connector. It worked great, and at a first glance the syncing seems to work flawlessly. Note though that it seems important to first set up CalDAV to be able to do the CardDAV synchronization.

[1]https://archive.is/TZfja
[2]https://web.archive.org/web/20150910162914/https://help.hover.com/entries/64466064-CalDAV-and-CardDAV-Synchronization-for-Thunderbird