dockerfile.run

addcr

command-line tools for building TCP client-server applications (IPv6)

Debian

RUN apt-get update && \
    apt-get install -y courier-mta

Ubuntu

RUN apt-get update && \
    apt-get install -y courier-mta

Kali Linux

RUN apt-get update && \
    apt-get install -y ucspi-tcp

Raspbian

RUN apt-get update && \
    apt-get install -y courier-mta

click the source code to copy install addcr on any operating system with command-not-found.com