Thunderbird, why not in discovery. Alternative email software

[Teunis]

I'd like to complete answering the original post by explaining how easy it is to back up Thunderbird.

Open Dolphin and do Alt+. this will show the hidden files and directories.

Now find .thunderbird directory and copy it to your back up drive.
Done.

[jglen490]

I didn't use it, but Discover in 18.04 does have Thunderbird, under the Internet subdivision. I just used Muon to install T-Bird and Lightning.

Discover has some shortcomings, but like everything else in Linux there are many other ways to do the same thing.