Install libesmtp6 by entering the following commands in the terminal:
sudo apt update sudo apt install libesmtp6
Description:
LibESMTP SMTP client library
LibESMTP is a library to manage posting (or submission of) electronic mail using SMTP to a preconfigured Mail Transport Agent (MTA) such as Exim. It may be used as part of a Mail User Agent (MUA) or another program that must be able to post electronic mail but where mail functionality is not the program's primary purpose.
Homepage: http://www.stafford.uklinux.net/libesmtp/
Version: 1.0.6-4.3build1
Section: libs