ImageGear.Formats.Email functionality relies on a library called "wkhtmltopdf". On Windows we install this as part of the Accusoft.ImageGear.Email NuGet package. On Linux there are different binaries for various Linux distributions. Therefore we need the user to install their own copy of wkhtmltopdf matched to their distribution. Below are commands you can use to install wkhtmltopdf for your Linux distribution.

Centos 7

yum install wget -y && \
wget -q https://github.com/wkhtmltopdf/packaging/releases/download/0.12.6-1/wkhtmltox-0.12.6-1.centos7.x86_64.rpm && \
yum install -y localinstall wkhtmltox-0.12.6-1.centos7.x86_64.rpm && \
wkhtmltopdf -V

Debian 10

apt-get update && \
apt-get install wget fontconfig xfonts-75dpi xfonts-base libjpeg62-turbo libx11-6 libxext6 libxrender1 libfreetype6  -y && \
wget -q https://github.com/wkhtmltopdf/packaging/releases/download/0.12.6.1-2/wkhtmltox_0.12.6.1-2.bullseye_amd64.deb && \
dpkg -i wkhtmltox_0.12.6-1.buster_amd64.deb && \
wkhtmltopdf -V

Ubuntu 20.04

apt update && \
apt-get install wget fontconfig xfonts-75dpi xfonts-base libjpeg-turbo8 libx11-6 libxext6 libxrender1 glib2.0 -y && \
wget -q https://github.com/wkhtmltopdf/packaging/releases/download/0.12.6-1/wkhtmltox_0.12.6-1.focal_amd64.deb && \
dpkg -i wkhtmltox_0.12.6-1.focal_amd64.deb && \
wkhtmltopdf -V