libesmtp-dev binary package in Ubuntu Lunar amd64

 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.
 .
 This package contains the header files and the static version
 of the library.

Source package