Install libmsdw-smtp-perl by entering the following commands in the terminal:
sudo apt update sudo apt install libmsdw-smtp-perl
SMTP Client/Server modules from smtpprox
Includes the Client.pm and Server.pm SMTP modules from smtpprox at http://bent.latency.net/smtpprox/ with Debian enhancements. . These modules are designed to expose every step of the protocol dialogue to the calling program, which provides for the greatest flexibility in hooking in envelope and content controls and scanning.