Fixing the huge emoji icons in Unbuntu 18.04 for Thunderbird

In Ubuntu 18.04, Thunderbird shows huge emoji icons in the email list. The emoji covers other text and is several lines higher and wider than other charactors. How to solve it?

This is likely caused by the fonts.

Find out the *emoji* fonts installed in your system by

sudo apt list *emoji*

and remove those *emoji* fonts by

sudo apt remove *emoji*

At last, to make sure the emoji fonts are still displayed nicely, install the fonts-symbola or another similar font by

sudo apt install fonts-symbola

Then refresh the fonts cache by

fc-cache -f

After restarting thunderbird, it should displays these emoji fonts well now.